update

documentation/source/BootROM_8890/boot_chain.rst

@@ -11,15 +11,48 @@ TODO document normal samsung boot chain
 Exploitation
 ============
 
-After exploitation the goal is to fully boot the device. 
+After exploitation the goal is to fully boot the device. The following part describes the current boot chain
 
-Current boot chain:
+.. important::
 
-.. figure:: images/boot_chain.drawio.svg
+    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:
+
+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.
+
+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
+   :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.
+
+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
@@ -256,6 +289,7 @@ bl1 interacts with several pheriperals, from the DTB these are:
 		clock-names = "gate_rtc";
 	};
 
+Probably the only thing it does is set some clocks and prepare for BL31
 
 BL31
 ----

documentation/source/BootROM_8890/notes.rst

@@ -0,0 +1,16 @@
+========
+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:: ghidra
+
+
+             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
+

reven/SamsungS7.lock

@@ -1,9 +0,0 @@
-#Ghidra Lock File
-#Thu Aug 15 13:43:49 CEST 2024
-OS\ Name=Linux
-OS\ Version=6.5.0-44-generic
-Username=eljakim
-Hostname=levith
-<META>\ Supports\ File\ Channel\ Locking=Channel Lock
-OS\ Architecture=amd64
-Timestamp=8/15/24, 1\:43 PM

reven/SamsungS7.rep/idata/00/00000002.prp

@@ -4,7 +4,7 @@
         <STATE NAME="EXCLUSIVE" TYPE="boolean" VALUE="false" />
         <STATE NAME="CHECKOUT_VERSION" TYPE="int" VALUE="-1" />
         <STATE NAME="CONTENT_TYPE" TYPE="string" VALUE="Program" />
-        <STATE NAME="PARENT" TYPE="string" VALUE="/" />
+        <STATE NAME="PARENT" TYPE="string" VALUE="/s7/dump" />
         <STATE NAME="FILE_ID" TYPE="string" VALUE="7f011889d240069673442230" />
         <STATE NAME="FILE_TYPE" TYPE="int" VALUE="0" />
         <STATE NAME="LOCAL_CHECKOUT_VERSION" TYPE="int" VALUE="-1" />

reven/SamsungS7.rep/idata/~index.bak

@@ -1,9 +1,7 @@
 VERSION=1
 /
   00000006:8890_bootrom.bin:7f0119bc3142241939494339
-  0000000a:8890_bootrom.bin.1:7f011a6853998629050259
+  0000000a:8890_bootrom_bl31_loaded:7f011a6853998629050259
-  00000002:8890_bootrom.bin.keep:7f011889d240069673442230
-  00000008:8890_bootrom_old_bl1:7f011822f30596451841878
 /dump
   00000009:reloc_debugger.elf:7f0119bd531451643843511
 /mib3
@@ -13,5 +11,8 @@ VERSION=1
   00000003:bl31.bin:7f011ab837995028720085
   00000004:sboot.bin.3.bin:7f011872b8163836628792
   00000005:sboot.bin.4.bin:7f011842b8231996037592
+/s7/dump
+  00000002:8890_bootrom.bin.keep:7f011889d240069673442230
+  00000008:8890_bootrom_old_bl1:7f011822f30596451841878
 NEXT-ID:b
 MD5:d41d8cd98f00b204e9800998ecf8427e

reven/SamsungS7.rep/idata/~index.dat

@@ -1,9 +1,7 @@
 VERSION=1
 /
   00000006:8890_bootrom.bin:7f0119bc3142241939494339
-  00000002:8890_bootrom.bin.keep:7f011889d240069673442230
   0000000a:8890_bootrom_bl31_loaded:7f011a6853998629050259
-  00000008:8890_bootrom_old_bl1:7f011822f30596451841878
 /dump
   00000009:reloc_debugger.elf:7f0119bd531451643843511
 /mib3
@@ -13,5 +11,8 @@ VERSION=1
   00000003:bl31.bin:7f011ab837995028720085
   00000004:sboot.bin.3.bin:7f011872b8163836628792
   00000005:sboot.bin.4.bin:7f011842b8231996037592
+/s7/dump
+  00000002:8890_bootrom.bin.keep:7f011889d240069673442230
+  00000008:8890_bootrom_old_bl1:7f011822f30596451841878
 NEXT-ID:b
 MD5:d41d8cd98f00b204e9800998ecf8427e

reven/SamsungS7.rep/user/~index.bak

@@ -4,7 +4,8 @@ VERSION=1
   00000004:udf_7f011842b8231996037592:7f01190f112184430945139
   00000003:udf_7f011872b8163836628792:7f011a9478217161533597
   00000001:udf_7f0119bc3142241939494339:7f011abb7142807435236045
+  00000006:udf_7f0119bd531451643843511:7f011a1c131523520933550
   00000005:udf_7f011a0d5252765509589854:7f0118e15255467845445248
   00000002:udf_7f011ab837995028720085:7f0118cdd8148515697603
-NEXT-ID:6
+NEXT-ID:7
 MD5:d41d8cd98f00b204e9800998ecf8427e

reven/SamsungS7.rep/user/~index.dat

@@ -6,6 +6,7 @@ VERSION=1
   00000001:udf_7f0119bc3142241939494339:7f011abb7142807435236045
   00000006:udf_7f0119bd531451643843511:7f011a1c131523520933550
   00000005:udf_7f011a0d5252765509589854:7f0118e15255467845445248
+  00000007:udf_7f011a6853998629050259:7f011a98934430536471611
   00000002:udf_7f011ab837995028720085:7f0118cdd8148515697603
-NEXT-ID:7
+NEXT-ID:8
 MD5:d41d8cd98f00b204e9800998ecf8427e

reven/SamsungS7.rep/user/~journal.bak

@@ -1,2 +1,2 @@
-IADD:00000006:/udf_7f0119bd531451643843511
+IADD:00000007:/udf_7f011a6853998629050259
-IDSET:/udf_7f0119bd531451643843511:7f011a1c131523520933550
+IDSET:/udf_7f011a6853998629050259:7f011a98934430536471611

source/emulator/.vscode/launch.json

@@ -0,0 +1,15 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Exynos Emultor",
+            "type": "debugpy",
+            "request": "launch",
+            "program": "emulator.py",
+            "console": "integratedTerminal"
+        }
+    ]
+}

source/emulator/emulator.py

@@ -0,0 +1,36 @@
+from ghidra_assistant.utils.utils import *
+from ghidra_assistant.utils.archs.arm64.arm64_emulator import ARM64UC_Emulator
+from unicorn.arm64_const import *
+from unicorn.unicorn_const import *
+
+class ExynosEmulator(ARM64UC_Emulator):
+    def __init__(self, rom_path):
+        super().__init__()
+        self.rom_path = rom_path
+        self.setup()
+        
+    def setup(self):
+        self.setup_memory()
+        self.setup_registers()
+        
+    def setup_memory(self):
+        #ROM
+        self.uc.mem_map(0x0, 128 * KB, UC_PROT_READ | UC_PROT_EXEC)
+        self.uc.mem_write(0x0, open(self.rom_path, "rb").read())
+        pass
+    
+    def setup_registers(self):
+        self.pc = 0x0
+        self.uc.reg_write(UC_ARM64_REG_PC, self.pc)
+        
+    def run(self):
+        try:
+            self.uc.emu_start(self.pc, self.pc + 1)
+            pass
+        except Exception as e:
+            self.print_ctx(print)
+            pass
+        
+if __name__ == '__main__':
+    emulator = ExynosEmulator("../S7/rom.bin")
+    emulator.run()

source/exploit/exploit.py

@@ -385,6 +385,23 @@ class ExynosDevice():
         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)
+
+        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 dumb_interact(self, dump_imems=False):
         '''
@@ -612,15 +629,43 @@ class ExynosDevice():
         
         # ==== BL31 ====
         assert self.usb_read(0x200) == b"GiAs", "Failed to jump back to debugger"
-        self.cd.memwrite_region(0x020200dc, p32(hijacked_fun)) # To continue booting next stages
+        
-        self.cd.restore_stack_and_jump(hijacked_fun)
+        self.cd.memwrite_region(self.cd.arch_dbg.state.X0, open("../S7/g930f_latest/g930f_sboot.bin.2.bin", "rb").read())
+        
+        
+        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
         time.sleep(2)
         self.connect_device()
+        
+                
 
-        self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.2.bin", "rb").read())
+        self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.2.bin", "rb").read()[:0x10])
+        time.sleep(2)
+        
+        self.usb_read(0x200) # GiAs
+        # lr = self.cd.arch_dbg.state.LR
+        self.cd.memwrite_region(0x020200dc, p32(hijacked_fun))
+        GADGET_RET0 = 0x00000d58
+        self.cd.memwrite_region(0x020200e4, p32(GADGET_RET0))
+        
+        # ====== PATCHES TO BL31 here! ======
+        # TODO fix not checking signatures
+        # self.cd.memwrite_region(0x02031008, b"ELH")
+        # 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)
+        self.cd.restore_stack_and_jump(lr)
+        
         time.sleep(2)
         self.connect_device()
-        time.sleep(1)
+        
+        
+        # self.usb_read(0x200) # GiAs
+        # 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())
@@ -629,9 +674,17 @@ class ExynosDevice():
 
 
         # ==== Stage 4  ====
-        self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.4.bin", "rb").read())
+        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"
+        self.send_normal_stage(stage4)
         time.sleep(2)
-        self.connect_device()
+
         pass
 
 

source/gupje_device/device.h

@@ -25,8 +25,8 @@ int mystrlen(char *data) {
 #define recv_buffer 0x020c6200 
 #define data_received 0x020c6000
 #else
-#define recv_buffer 0x206fe00 //0x02021800 + 0x3000
+#define recv_buffer 0x206f000 //0x02021800 + 0x3000
-#define data_received 0x206fd00
+#define data_received 0x206f100
 #endif
 
 void recv_data_cb(uint32_t endpoint, uint32_t len){

source/gupje_device/reloc2_linkscript.ld

@@ -0,0 +1,14 @@
+MEMORY {
+    ROM (rwx): ORIGIN = 0x020c0000, LENGTH = 0x1000
+}
+
+SECTIONS
+{
+     . = 0x020c0000;
+     .text . : {
+          *(.text*)
+          *(.data*)
+          *(.rodata*)
+     } >ROM
+
+}

source/gupje_device/reloc2_symbols.txt

@@ -0,0 +1,12 @@
+debugger_storage = 0x020c4000;
+debugger_stack = 0x020c2000;
+debugger_entry = 0x020c0000;
+
+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 = 0x020c6200;
+g_data_received = 0x020c6000;