2021from public repositories
setodaNote CTF 2021
3 challenges with 4 published solutions between them. The writeups for this event were found in public repositories. Each link is pinned to the commit it was read from.
Where these writeups liveCryptography1
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 decoderVigenere cipher solver with automatic key recoveryRSA decryption and attack runnerWiener’s attack on small RSA private exponentsIn-browser hash cracker with rule transformsLearn: Classical ciphers and frequency analysisLearn: RSA and the parameters that break it
Also written up in: mikecat/ctf-writeups
Binary exploitation1
Turn a memory-safety bug in a native binary into control of execution. Usually a stack overflow, a format string, or a heap primitive.
Solve it with:ROP gadget finderShellcode assembler and libraryCyclic pattern generator and offset finderFormat string exploit builderLearn: Binary exploitation
Shellcode
2 official solutionsAlso written up in: mikecat/ctf-writeups, mikecat/ctf-writeups
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 blobsWebAssembly disassemblerJava .class disassemblerPython .pyc bytecode disassemblerLearn: Binary exploitation
To Analyze
1 official solutionAlso written up in: mikecat/ctf-writeups