RACF bits and pieces

24 April 2018

Extracting password history from RACF

by Jim

With thanks to Dhiru Kholia, who was able to tidy up the “mystery” racf_debug.c program, it is possible to extract old passwords for IDs from a RACF database. Unfortunately this is one downside to having an extensive password history enabled on a system - e.g. SETROPTS HISTORY(12) means that 12 old passwords are retained in the RACF database to ensure users do not re-use their passwords. It also means that all 12 password hashes are also stored…

Q: Why would you want the old hashes?
A: Why not? 😃 Apart from idle curiosity, a genuine use would be to track password patterns used which could allow you to predict future passwords for an ID

  1. Save the code to your PC (or clone the repo if you prefer)

  2. On a Unix-like system, compile and run it (if using macOS you will need to have Xcode and the command line tools installed to use gcc): gcc racf-debug-cleanup.c -o racf-debug-cleanup; ./racf-debug-cleanup SYS1.RACFDB | grep '\$racf' > hashes.txt

  3. Use the resulting hashes.txt file in hashcat

tags: RACF - passwords