2021weight 24.98JohnHammond

H@cktivityCon 2021 CTF

48 challenges with 158 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

Misc17

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 decoder Cipher identifier and automatic decoder Regex tester with match offsets and capture groups Learn: Recognising encodings

Tsunami
50 pts8 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
2ez
50 pts7 writeups
- warmup
- warm-up
Same technique in picoCTF: Permissions, Specialer, Codebook
ButterOverflow
50 pts7 writeups
- bufferoverflow
- warmups
Same technique in picoCTF: Permissions, Specialer, Codebook
OTP Smasher
283 pts6 writeups
- ocr
- scripting
Same technique in picoCTF: Permissions, Specialer, Codebook
Six Four Over Two
50 pts6 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Bad Words
50 pts5 writeups
- miscellaneous
Same technique in picoCTF: Permissions, Specialer, Codebook
Pimple
50 pts5 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Read The Rules
50 pts5 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Redlike
115 pts5 writeups
- miscellaneous
Same technique in picoCTF: Permissions, Specialer, Codebook
Target Practice
50 pts5 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Bass64
50 pts4 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Movie Marathon
444 pts3 writeups
- scripting
Same technique in picoCTF: Permissions, Specialer, Codebook
Shelle
50 pts3 writeups
- misc
- miscellaneous
Same technique in picoCTF: Permissions, Specialer, Codebook
Words Chruch
407 pts3 writeups
- scripting
Same technique in picoCTF: Permissions, Specialer, Codebook
Oddball
50 pts2 writeups
- warmup
Same technique in picoCTF: Permissions, Specialer, Codebook
Race Car
478 pts2 writeups
- miscellaneous
Same technique in picoCTF: Permissions, Specialer, Codebook
Dotbat
466 pts1 writeup
- exe
- deobfuscation
- malware
- windows
- batch
Same technique in picoCTF: Permissions, Specialer, Codebook

Web10

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 verifier JWT alg=none bypass generator Web attack payload catalog JWT secret brute force Learn: Web attacks and session tokens

Phonetic
362 pts6 writeups
- deobfuscation
- php
- malware
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
Confidentiality
50 pts4 writeups
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
OPA Secrets
298 pts4 writeups
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
Titanic
50 pts4 writeups
- misconfiguration
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
Bumblebee
491 pts3 writeups
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
Go Blog
500 pts2 writeups
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
SpiralCI
496 pts2 writeups
- web
- npm
- nodejs
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
Swaggy
50 pts2 writeups
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3
All Baked Up
359 pts1 writeup
- sqlite
- web
- graphql
Same technique in picoCTF: Irish-Name-Repo 3, More SQLi, Secret Box
Unpugify
480 pts1 writeup
- web
Same technique in picoCTF: Client-side-again, dont-use-client-side, Irish-Name-Repo 3

Binary exploitation9

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 finder Shellcode assembler and library Cyclic pattern generator and offset finder Format string exploit builder Learn: Binary exploitation

Faucet
413 pts3 writeups
- pwn
- printf
- binaryexploitation
Same technique in picoCTF: Guessing Game 1, x-sixty-what, format string 3
Integrity
50 pts2 writeups
- restricted-bash
- escapeshellcmd
- shell
Same technique in picoCTF: Guessing Game 1, x-sixty-what, format string 3
pawned
494 pts2 writeups
- binary-exploitation
- heap
Same technique in picoCTF: tea-cash, sice_cream, zero_to_hero
sharp
500 pts2 writeups
- heap
- pwn
Same technique in picoCTF: tea-cash, sice_cream, zero_to_hero
shellcoded
400 pts2 writeups
- pwn
Same technique in picoCTF: Binary Gauntlet 2, ropfu, solfire
Shelle-2
493 pts2 writeups
- binary-exploitation
Same technique in picoCTF: Guessing Game 1, x-sixty-what, format string 3
The_library
362 pts2 writeups
- pwn
Same technique in picoCTF: Guessing Game 1, x-sixty-what, format string 3
YABO
478 pts2 writeups
- pwn
Same technique in picoCTF: Guessing Game 1, x-sixty-what, format string 3
retcheck
277 pts1 writeup
- bof
- pwn
- ret2win
- rop
Same technique in picoCTF: Guessing Game 1, x-sixty-what, handoff

Cryptography4

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 decoder Vigenere cipher solver with automatic key recovery RSA decryption and attack runner Wiener’s attack on small RSA private exponents In-browser hash cracker with rule transforms Learn: Classical ciphers and frequency analysis Learn: RSA and the parameters that break it

N1TP
50 pts8 writeups
- one-time-pad
- crypto
Same technique in picoCTF: StegoRSA, Timestamped Secrets, AES-ABC
Hexahedron
50 pts4 writeups
- cryptography-rsa
Same technique in picoCTF: StegoRSA, john_pollard, rsa_oracle
Sausage Links
468 pts3 writeups
- crypto
- rsa
Same technique in picoCTF: StegoRSA, john_pollard, rsa_oracle
Triforce
444 pts1 writeup
- aes
- crypto
Same technique in picoCTF: Timestamped Secrets, AES-ABC, Compress and Attack

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 bytes Magic byte and file signature table PCAP analyzer for CTF network forensics EXIF metadata viewer Learn: File forensics and carving Learn: Network forensics

UHAHA
417 pts3 writeups
- forensics
- misc
- digital
- miscellaneous
- digital-forensics
- scripting
Same technique in picoCTF: FindAndOpen, c0rrupt, extensions
Excellent
479 pts2 writeups
- forensics
Same technique in picoCTF: FindAndOpen, c0rrupt, extensions
Bacon in a Haystack
492 pts1 writeup
- forensics
Same technique in picoCTF: FindAndOpen, c0rrupt, extensions

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 viewer QR code decoder

Jed Sheeran
50 pts3 writeups
- osint
Same technique in picoCTF: Permissions, Specialer, Codebook
Don T Mason
482 pts1 writeup
- osint
Same technique in picoCTF: Permissions, Specialer, Codebook
Mike Shallot
411 pts1 writeup
- osint
Same technique in picoCTF: Permissions, Specialer, Codebook

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 blobs WebAssembly disassembler Java .class disassembler Python .pyc bytecode disassembler Learn: Binary exploitation

To Do
50 pts5 writeups
- mobile
Same technique in picoCTF: WinAntiDbg0x100, WinAntiDbg0x200, WinAntiDbg0x300
Reactor
383 pts2 writeups
- mobile
Same technique in picoCTF: WinAntiDbg0x100, WinAntiDbg0x200, WinAntiDbg0x300

Misc17

Tsunami

2ez

ButterOverflow

OTP Smasher

Six Four Over Two

Bad Words

Pimple

Read The Rules

Redlike

Target Practice

Bass64

Movie Marathon

Shelle

Words Chruch

Oddball

Race Car

Dotbat

Web10

Phonetic

Confidentiality

OPA Secrets

Titanic

Bumblebee

Go Blog

SpiralCI

Swaggy

All Baked Up

Unpugify

Binary exploitation9

Faucet

Integrity

pawned

sharp

shellcoded

Shelle-2

The_library

YABO

retcheck

Cryptography4

N1TP

Hexahedron

Sausage Links

Triforce

Forensics3

UHAHA

Excellent

Bacon in a Haystack

OSINT3

Jed Sheeran

Don T Mason

Mike Shallot

Reverse engineering2

To Do

Reactor

Other 2021 events