SANS Digital Forensics and Incident Response Blog: Author - Dave Hull

Metadata distributions in Computer Forensics

After my previous post, on using uid and gid distributions to spot malicious code on *nix file systems, I took to working on some code to convert *nix "modes" (The Sleuth Kit bodyfile refers to file type and permission information as mode) from fls bodyfiles to their octal representations and then to calculate averages and … Continue reading Metadata distributions in Computer Forensics


Digital Forensics: UID and GID distributions

On Unix and Linux systems each file has a user id and a group id, uid and gid respectively, showing the file's owner and group. On most *nix systems files in system directories are uid and gid root, which is represented by the numeric uid and gid value of 0, see the sample listing below: … Continue reading Digital Forensics: UID and GID distributions


Outlier analysis in digital forensics

In my previous post, Atemporal time line analysis in digital forensics, I talked about using the inodes of a known piece of attacker code as a pivot point to discover previously unknown attacker code on a system. In this post, I want to point out another interesting thing about these inodes. Recall that I'm using … Continue reading Outlier analysis in digital forensics


Atemporal time line analysis in digital forensics

As incident responders we often find that attackers compromise one host in a network and then pivot to others. In digital forensic investigations involving intrusions, we can do our own pivoting from one piece of evidence to another. On October 19th, I had the good fortune to speak at SECTor about one method of doing … Continue reading Atemporal time line analysis in digital forensics


Data reduction redux and map-reduce

A few days ago I wrote a post about applying the principle of least frequent occurrence to string searches in forensics. This post will discuss how long that process may take and at the end, will show some significant ways to speed up the process. In the previous post I used the following compound command … Continue reading Data reduction redux and map-reduce