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Every CTF
2015from public repositories

PCTF 2015

5 challenges with 9 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 live

Cryptography2

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

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

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

Uncategorised1

The upstream scoreboard did not say, so neither do we.

Solve it with:Cipher identifier and automatic decoderLearn: Recognising encodings

Other 2015 events