My personal writeup for Nebula from Andrew Griffits Exploit Education
Nebula takes the participant through a variety of common (and less than common) weaknesses and vulnerabilities in Linux. It takes a look at
SUID files
Permissions
Race conditions
Shell meta-variables
$PATH weaknesses
Scripting language weaknesses
Binary compilation failures
At the end of Nebula, the user will have a reasonably thorough understanding of local attacks against Linux systems, and a cursory look at some of the remote attacks that are possible.