Web exploitation
Find and chain vulnerabilities in web applications — the most common attack surface in production today.
SQLiXSSSSRFIDOR
Hands-on cybersecurity · self-paced CTF
Practice security by breaking things safely.
Build practical skills with hands-on challenges in a sandbox made for learning. Work at your own pace, submit flags, and see your progress on the scoreboard.
// platform brief
Learn by solving real problems, not just reading about them
Hack4Shell is a free, self-paced CTF for learning cybersecurity through practice. Investigate a challenge, test your ideas in a safe environment, and submit the flag when you solve it. Your account keeps track of your score and progress; event details, community writeups, and standings are here when you need them.
- Format
- Online, self-paced
- Practice
- Hands-on labs
- Start
- Free to play
More than challenges
Hands-on challenges, CTF events, and community writeups
Events
Find event details, follow competition updates, and revisit published results.
Explore eventsWriteups
Read community walkthroughs to compare approaches and learn from each solve.
Read writeupsLeaderboard
Track your points, see how you rank, and celebrate the community’s top solvers.
View standingsChallenge categories
Six security domains, from web challenges to disk images
Cryptography
Break weak schemes, exploit implementation flaws, and recover plaintext that was never supposed to come back.
RSAHashingSteganography
Reverse engineering
Read a binary the way its author never intended you to — disassemble, debug, and rebuild its logic in your head.
GhidraGDBx64dbg
Binary exploitation
Corrupt memory on purpose. Bypass modern mitigations and turn a bug into arbitrary code execution.
Buffer overflowHeapASLR bypass
Digital forensics
Reconstruct an intrusion after the fact from memory dumps, disk images, and packet captures.
Memory analysisPCAPDisk images
OSINT
Pull scattered public data into a coherent picture — the reconnaissance phase of every real engagement.
ReconMetadataSocial
footprint
Recognition
Hall of Fame
We recognize security researchers whose responsible disclosures protect users and strengthen the wider security community.
Meet the researchers