Breaking Systems For Fun And Profit

Six to Five

Published:  by Wander Boessenkool
Tags: login , sha , submitted , md5 , sha256

Another one from the old site, this one was submitted by Ed van der Salm

  sed -i 's/:$6/:$5/g' /etc/shadow

What it does

It changes all entries in /etc/shadow that use a sha256 hash to use a md5 hash, without actually changing the hash itself.

Why it works

Md5 hashes are not sha256 hashes, causing all logins using a password to fail.

TL;DR