WriteUp on how to crack a 7z password

Just my brain dump, for future use on how to crack a 7z password (as a CTF challenge of course 😉)

Required tools

• https://github.com/philsmd/7z2hashcat (to extract the hash from the .7z)
• https://hashcat.net/hashcat/ (hashcat binaries)
• https://developer.nvidia.com/cuda-downloads (CUDA software)

Word lists

I’ve had success with these any/or

• https://labs.nettitude.com/blog/rocktastic/ Rocktastic12a
• https://weakpass.com/wordlist/1947 weakpass_3
• https://weakpass.com/wordlist/1927 cyclone.hashesorg.hashkiller.combined.txt
• realuniq.lst
• realhuman_phill.txt

Rules for hashcat

• https://github.com/samirettali/password-cracking-rules/blob/master/best64.rule

Preparation

• Get all the tools installed
• Delete all OpenCL.dll, OpenCL32.dll, OpenCL64.dll files from system (hashcat kept picking OpenCL instead of CUDA in my case) as per this post

Extract the hash to crack

.\7z2hashcat64-1.9.exe mysession.7z

Save this hash to a file named myhash.txt

Lets launch hashcat on this hash

NOTE: use rules

.\hashcat.exe --hash-type 11600 myhash.txt --attack-mode 0 --outfile 4080super_try.txt --keep-guessing .\cyclone.hashesorg.hashkiller.combined.txt
.\hashcat.exe --hash-type 11600 new_try.txt --attack-mode 0 --outfile 4080super_try.txt --rules-file best64.rule --keep-guessing .\Rocktastic12a

.\cyclone.hashesorg.hashkiller.combined.txt is too heavy for rules 

.\hashcat.exe --hash-type 11600 new_try.txt --attack-mode 0 --outfile 4080super_try.txt --keep-guessing -.\cyclone.hashesorg.hashkiller.combined.txt
.\hashcat.exe --hash-type 11600 new_try.txt --attack-mode 0 --outfile 4080super_try.txt --rules-file best64.rule --keep-guessing .\realhuman_phill.txt