$ ctf42

Reverse CTF challenges

4,044 Reverse CTF challenges from 397 CTFs (2011–2026), 511 with writeups.

Top reverse techniques

#reversing 77 #xor 24 #z3 15 #vm-reversing 13 #constraint-solving 10 #static-analysis 9 #strings 9 #android 9 #anti-debugging 7 #symbolic-execution 6 #dotnet-reversing 6 #xor-cipher 5 #angr 5 #windows-reversing 5 #binary-patching 5

Challenges

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Challenge CTF Weight Has
Recurso
#custom-vm-reversing
 K3RN3LCTF 2021 24.37 files wu 1
Reduced_Reduced_Instruction_Set_2
#custom-vm#bytecode-reversing#z3
 PatriotCTF 2023 24.52 files wu 1
Bussin
#custom-file-format#qoi
 BlueHens 2023 24.61 files wu 1
File.tetr
#custom-encoding#run-length-encoding
 UTCTF 2021 – files wu 1
AlphaCode
#custom-dsl-reversing#opcode-fuzzing
 BoroCTF 2026 – files wu 1
Control_Freak_1
#custom-cipher-reversing
 LYKNCTF 2026 – files wu 1
Self-HostedCrypto
#custom-cipher
 HackPack 2022 35.11 files wu 1
cuCRACKME
#cuda-reversing#gpu-reversing
 VolgaCTF 2024 Quals 35.91 files wu 1
Sabloom_Text_6
#crackme#windows-reversing#xor#maze-solving
 Zh3r0 2021 – files src wu 1
rediary
#cpp-reversing#custom-cipher
 S4CTF 2021 24.52 files wu 1
Algorithm
#cpp-reversing#bfs#graph
 UTCTF 2021 – files wu 1
coregasm
#core-dump-analysis
 PlaidCTF 2022 93.67 files wu 1
drum_machine
#constraint-solving
 LakeCTF 2025 Quals – files wu 1
purely_functional_oop
#compiler-exploitation#google-sheets
 corCTF 2025 82.00 files wu 1
Compile_Me
#compile-and-run
 Mapna 2024 24.59 files wu 1
reverse_cipher
#char-shift-cipher#ghidra
 picoCTF 2019 – files wu 1
HaRlEm_ShAkE
#chacha20-poly1305
 hxp 2024 – files wu 1
Knights_Droid
#caesar-cipher
 KnightCTF 2025 18.78 files wu 1
compilerhell
#c-preprocessor#macro-metaprogramming
 S4CTF 2021 24.52 files wu 1
Borrowed_Memory
#bytecode-vm-emulation#xorshift-table-regeneration#checksum-guided-debugging#xor-decryption
 BDSec 2026 15.62 files wu 1
simple_cipher
#byte-at-a-time-bruteforce
 TAMUctf 2021 – files wu 1
vault-door-4
#byte-array-decoding
 picoCTF 2019 – files wu 1
dht
#bruteforce#thread-race#search-pruning
 RCTF 2021 – files wu 1
Cube_Hash
#brute-force
 Hack.lu 2023 94.73 files wu 1
Time_Machine
#brute-force
 FwordCTF 2021 24.42 files wu 1
Waguri2
#brainfuck-esolang
 LYKNCTF 2026 – files wu 1
Brain
#brainfuck-esolang
 n00bzCTF 2024 24.23 files wu 1
F_K
#brainfuck#timing-side-channel
 ScriptCTF 2026 – files wu 1
My_Brain_Hurts
#brainfuck
 BCACTF 2024 – files wu 1
No_Thoughts_Head_Empty
#brainfuck
 ImaginaryCTF 2021 – files wu 1
vault-door-8
#bit-transposition
 picoCTF 2019 – files wu 1
Retrosynthesis
#binary-patching
 idekCTF 2021 24.56 files wu 1
befudged_up
#befunge#side-channel#brute-force
 WolvCTF 2024 35.25 files wu 1
vault-door-5
#base64#url-encoding
 picoCTF 2019 – files wu 1
BashD00R
#backdoored-bash-binary#code-in-data-section
 Aero 2021 35.17 files wu 1
What_is_it
#autoit-decompilation#script-deobfuscation
 CYBERGON 2023 – files wu 1
Painting_Windows
#anti-debugging#xor#windows-reversing
 UMDCTF 2021 – files wu 1
YAY
#anti-debugging#unpacking
 Securinets 2021 Quals 41.71 files wu 1
Confusion
#anti-debugging#reversing
 VishwaCTF 2022 20.79 files wu 1
molly
#anti-debugging#instrumentation-callback
 TRX 2025 – files wu 1