reversehard

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hackerlab

Task: Reverse engineer a WinRAR SFX-wrapped PE executable with anti-debug and decoy flag. Solution: Discovered self-modifying code in PE overlay that decrypts hidden ChaCha20 verification shellcode using SUB+XOR transformation.

$ ls tags/ techniques/

xor mingw shellcode chacha20 anti_debug self_modifying_code sfx_unpacking decoy_flag pe_overlay virtualprotect

WinRAR SFX unpackingDecoy flag identification via XOR decodingSelf-modifying code analysis in PE overlayRuntime shellcode decryption (SUB+XOR)ChaCha20 parameter extraction from x86-64 assemblyObfuscated constant recovery via XOR with 0xa5a5a5a5

Analysis

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

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