Where can I find obfuscated ELF binaries to practice reverse engineering techniques specifically for obfuscated binaries?

Question

I’m trying to get better at reverse engineering obfuscated code (and malware in general) and I’m looking for already obfuscated binaries with increasing levels of difficulty. I’ve looked a bit on crackmes.one (not extensively), but was hoping for some kind of level-based resource specifically for obfuscated binaries (preferably ELF)

Answer 1

The French ANSSI organizes a reverse engineering contest covering different fields: crypto, forensics, hardware, ... It's a good start.

Binaries and other challenges are available here: https://hackropole.fr/en/challenges/

I would also recommend playing around and trying to reverse real life malware (in a sandboxed VM of course). You can find plenty of binaries here:

1. https://bazaar.abuse.ch/browse
2. https://github.com/Endermanch/MalwareDatabase

Happy hacking!

Answer 2

I would add that you can also:

1. Search on blogs of cybersecurity companies - they often provide writeups on some malware and add the hash of related executables/files.
2. Look for those hashes on VirusTotal. You can download a sample and then deal with a real malware and you'll have a writeup on what it does to help you.
3. Do the flareon challenge, it's a nice reversing challenge that can help you learn and get better: https://flare-on.com/

Some additional references:

• https://virustotal.com
• https://www.welivesecurity.com/en/our-experts/eset-research/