2021weight 22.30Cryptonite

NITECTF

4 challenges with 6 published community solutions between them. Solution links go to CTFtime’s task page, which aggregates every writeup for a challenge - individual blog posts rot, the aggregator does not.

Full task list on CTFtime

Cryptography3

Recover a plaintext or a key from something that was supposed to protect it. In practice: identify the scheme, find the parameter the author got wrong, exploit it.

Solve it with:Cipher identifier and automatic decoder Vigenere cipher solver with automatic key recovery RSA decryption and attack runner Wiener’s attack on small RSA private exponents In-browser hash cracker with rule transforms Learn: Classical ciphers and frequency analysis Learn: RSA and the parameters that break it

CBC-Jail
457 pts2 writeups
- pyjail
- aes
- pwn
- crypto
- iv
Same technique in picoCTF: Timestamped Secrets, AES-ABC, Compress and Attack
Rabin to The Rescue
371 pts2 writeups
- crypto
Same technique in picoCTF: StegoRSA, Timestamped Secrets, AES-ABC
Flip Me Over
443 pts1 writeup
- aes-cbc
- crypto
Same technique in picoCTF: Timestamped Secrets, AES-ABC, Compress and Attack

Reverse engineering1

Work out what a compiled program does without its source, then work backwards from the check to the input that passes it.

Solve it with:Strings extractor for binaries and blobs WebAssembly disassembler Java .class disassembler Python .pyc bytecode disassembler Learn: Binary exploitation

Lost Dungeon
500 pts1 writeup
- game
- unity
- rev
- windows
Same technique in picoCTF: WinAntiDbg0x100, WinAntiDbg0x200, WinAntiDbg0x300

Cryptography3

CBC-Jail

Rabin to The Rescue

Flip Me Over

Reverse engineering1

Lost Dungeon

Other 2021 events