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2021from the authors’ own sites

Sieberrsec 3.0 CTF 2021

6 challenges with 6 published solutions between them. CTFtime has no listing for this event at all, so nothing built on CTFtime can show what it was made of. These writeups were found on the authors’ own sites instead.

Where these writeups live

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 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

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 decoderCipher identifier and automatic decoderRegex tester with match offsets and capture groupsLearn: Recognising encodings

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

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

Other 2021 events