Writeups for various CTFs competitions.
On this page you can find links to writeups for the following categories:
- Blockchain
- Cryptography
- Forensics
- Cheating in games
- Miscellaneous
- OSINT
- Pwn
- Brute-forcing passwords
- Quantum cryptography
- Reverse engineering
- Web
You can also find a list of useful CTF tools.
- Blockchain transactions are public (ETH)
- Reentrancy exploit
- Set up of environment, underflow and reentrancy
- OTP reuse
- Morse from audio
- Enigma
- Enigma avec IC
- Lot of guessy ciphertexts without knowledge of cipher
- Hill cipher
- Malleability of the first block in AES-CBC
- Padding oracle attack on AES-CBC
- IV recovery with partially known plaintext, ciphertext and key in AES-CBC
- Exploiting predictable IV in AES-CBC
- Differential Power Analysis on first round of AES
- RSA with ciphertext super small
- Attacks on RSA: Wiener, sexy primes, LSB oracle, partial private key leaked
- Multi-primes RSA
- Fixed point in RSA
- RSA full oracle
- DLP, order of N has small factors
- ElGamal signature scheme without hash existential forgery
- Break DH key exchange with Pohlig-Hellman attack for DLP
- Oracle for finding secret exponent
- Shamir polynomial with linked coefficients
- Retrieve state of java.util.Random PRNG
- Solve system of integer inequalities - java.util.Random calls
- Custom VHDL cipher on FPGA
- Hardware AES key, CRT, Galois fields
- Encryption oracle with plaintext compressed
- Example in RUST
- Broken JPEG header
- Broken PNG image
- Broken BMP header
- Flag hidden in bit plane of image
- Image manipulation with PIL
- Hidden flag in PNG (zsteg)
- Hidden flag in scanline filter of PNG
- Code128
- Piet
- binwalk and flag hidden in spectrogram of audio file
- UART
- SSTV
- Some signal analysis (Winlink)
- WAV file is an oscilloscope input
- Android dump position history
- Arduino
- Analyse dump file with volatility
- Analyse Windows file with volatility
- Windows recurring task
- Repair RAID files
- Backdoor in service (systemd)
- ELF Core dump
- Polyglotte files
- Hidden flag in RSA parameter
- Detect falsified data with Benford's law
- Automating decompression with password cracking
- Read sparse files
- Color hex values
- Sound keylogger
- Elastic search
- Log4Shell
- Bypass float comparison in Python
- Read QR code with Python
- Python bytecode
- Create Signal with a given frequency
- Homoglyphes
- Reverse gzdeflate
- Captcha brute force
- Become root in VM
- Github older commit
- Old version of pip library
- Find password of an employee in social network
- Old version of website
- Simple buffer overflow
- 32 bits ROP chain buffer overflow
- NX disabled
- Write shellcodes with restrictions
- Get a shell using dup2 and execv with ROP
- Format string vulnerability to bypass canary and PIE for buffer overflow
- GOT override with format string vulnerability (no PIE)