2024weight 49.48InfoSecIITR

BackdoorCTF 2024

3 challenges with 3 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

Cryptography1

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

I Like McDonalds
100 pts1 writeup
- crypto
- hash
Same technique in picoCTF: hashcrack, It is my Birthday 2, StegoRSA

Forensics1

Recover something from a file, a capture, or a disk image - often from a part of it the format says is unused.

Solve it with:File type identifier by magic bytes Magic byte and file signature table PCAP analyzer for CTF network forensics EXIF metadata viewer Learn: File forensics and carving Learn: Network forensics

Cursed Credential
100 pts1 writeup
- rockyou.txt
- forensics
- password-cracking
- hashcat
Same technique in picoCTF: WPA-ing Out, FindAndOpen, c0rrupt

Misc1

Everything that fits no other box: esolangs, puzzles, scripting exercises, and the jail escapes that have not yet earned their own category.

Solve it with:Brainfuck and esolang decoder Cipher identifier and automatic decoder Regex tester with match offsets and capture groups Learn: Recognising encodings

Decompressor
453 pts1 writeup
- huffman
- misc
- compression
Same technique in picoCTF: Permissions, Specialer, Codebook

Cryptography1

I Like McDonalds

Forensics1

Cursed Credential

Misc1

Decompressor

Other 2024 events