cryptoPromedium

Undervattensströmmar

undutmaning

Task: LCG-based XOR stream cipher with missing parameters, known file header. Solution: Known plaintext attack to recover keystream, GCD method to crack LCG parameters, decrypt and extract flag from gzip/tar archive.

gzip known_plaintext lcg stream_cipher tar xor

gcd_attackknown_plaintext_attacklcg_parameter_recoverymodular_inverse

$ ls tags/ techniques/

gzip known_plaintext lcg stream_cipher tar xor

gcd_attackknown_plaintext_attacklcg_parameter_recoverymodular_inverse

Analysis

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

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

Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Permission denied (requires tier.pro)

Sign in to access full writeups

$sign in

$ cat writeup.md…

Sign in to access full writeups

Sign in to access full writeups

Similar writeups