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Every CTF
2021weight 17.90Securebug

Securebug.se CTF Odin 2021

21 challenges with 55 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

Web7

Reach data or functionality the application meant to keep from you - through its inputs, its tokens, or its trust in the client.

Solve it with:JWT decoder and signature verifierJWT alg=none bypass generatorWeb attack payload catalogJWT secret brute forceLearn: Sessions, tokens and access control

Uncategorised4

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

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

Forensics3

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 bytesMagic byte and file signature tablePCAP analyzer for CTF network forensicsEXIF metadata viewerLearn: File forensics and carvingLearn: Network forensics

OSINT3

Answer a question about the real world from public sources. The work is pivoting between identifiers, not exploiting anything.

Solve it with:EXIF metadata viewerQR code decoder

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 engineering2

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

Other 2021 events