IT Forensics · Linux

Forensic analysis of Linux user accounts – reconstructing accounts, groups and permissions

User accounts and their group memberships form the basis of access control in Linux. Their forensic analysis covers not only current accounts but also historical changes, as well as accounts created under unusual circumstances or privileged accounts.

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An account that has been newly created or subsequently granted extended privileges may be a strong indication of unauthorised compromise, particularly if it was created outside of standard administrative processes.

Why LanCologne?

Since its foundation, LanCologne has specialised in professional IT forensics. Our staff have decades of experience in the field of information technology and assist companies, solicitors, private individuals and, on a regular basis, the courts in the technical investigation of complex digital matters.

The examination is, as a matter of principle, carried out exclusively on a forensic copy, a forensic image or a data source captured in a technically equivalent manner that preserves the integrity of the evidence. The original evidence remains unchanged and is stored in a manner that preserves its integrity.

Our services

We analyse existing user accounts, group memberships and permission structures, identify suspicious or atypical accounts, and determine when they were created.

Typical areas of application

•Detection of unauthorised user accounts
•Investigation into subsequent extensions of rights
•Reconstruction of a system’s account history
•Assessment of group memberships with extended rights
•Incident Response on Linux Systems
•Judicial and non-judicial expert reports

This is how an analysis of user accounts is carried out

Once the backup has been completed, all existing user accounts and group memberships are recorded and compared with expected standard configurations. Accounts with administrative or extended privileges are checked separately; their creation dates are reconstructed using metadata and correlated with other system events.

Why is the analysis of user accounts relevant from a forensic perspective?

Creating an additional privileged account is one of the most direct ways of gaining permanent administrative access to a compromised system, which is why account lists are carefully checked.

Even accounts that appear unremarkable but have unusual group memberships may indicate a targeted, albeit less obvious, expansion of rights, and are therefore also taken into account.

Frequently Asked Questions

Where are user accounts stored on Linux?+
Basic account information in a central configuration file, password hashes in a separately protected file, and group memberships in other configuration files.
How can an unauthorised account be identified?+
By comparing them with known, expected accounts and checking the creation date, permissions and group memberships for plausibility.
Can deleted user accounts be recovered?+
In some cases, provided there are relevant log or filesystem remnants that indicate an account existed at some point in the past.

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LanCologne – Linux Forensics Cologne

Do you require a professional forensic investigation into „forensic analysis of Linux user accounts"? LanCologne can assist you with the legally admissible preservation of digital evidence and the transparent analysis of relevant Linux artefacts.

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