reversePromedium

Let's take a detour

ringzer0ctf

Task: a Windows PE32 console crackme uses an anti-debug DbgUiRemoteBreakin patch, a Detours-style hook on CreateThread, and a Vectored Exception Handler that redirects EIP, printing the flag only for the correct password. Solution: statically reverse the two detours and recover the XOR masks to derive the password and the printed flag.

reverse_engineering xor windows pe32 crackme anti_debug x86 api_hooking msvc detour vectored_exception_handler in_place_buffer_transform

static_disassemblyformat_string_flag_derivationinline_api_hook_analysisvectored_exception_handler_control_flowxor_mask_recoverytime_derived_key_identification

$ ls tags/ techniques/

reverse_engineering xor windows pe32 crackme anti_debug x86 api_hooking msvc detour vectored_exception_handler in_place_buffer_transform

static_disassemblyformat_string_flag_derivationinline_api_hook_analysisvectored_exception_handler_control_flowxor_mask_recoverytime_derived_key_identification

Analysis

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$ python3 exploit.py --target 192.168.1.1 --port 8080
[*] Connecting to target...
[+] Shell obtained!

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