IT Forensics · Linux

Forensic analysis of SSH authentication protocols – reconstructing remote access sessions in a traceable manner

SSH is the standard method for remote administrative access to Linux-Server and logs successful and failed authentication attempts, including the time, username and source IP address.

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These logs are often the key starting point for investigating Server compromises, particularly when combined with login histories and other security logs.

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 extract SSH authentication logs in their entirety, reconstruct successful and failed access attempts, and map these to the relevant user accounts and source addresses.

Typical areas of application

•Reconstruction of remote administrative access
•Investigation of brute-force and credential-stuffing attacks
•Evidence of unauthorised access from external addresses
•Reconciliation with login histories and other logs
•Incident Response on Linux Systems
•Judicial and non-judicial expert reports

This is how an SSH protocol analysis works

Once the data has been backed up, SSH authentication logs are extracted from Syslog or journald and organised chronologically. Successful and failed access attempts are analysed by username, authentication method and source address, and cross-referenced with other login logs such as wtmp and btmp.

Why is SSH analysis relevant in a forensic context?

The majority of unauthorised access to Linux-Server occurs via SSH, which is why the associated authentication logs regularly provide key evidence of the point of origin of a compromise.

The combination of the time, username, authentication method and source address often makes it possible to reconstruct the actual course of the attack with precision.

Frequently Asked Questions

What information do SSH authentication protocols contain?+
These include, amongst other things, the time, the user account concerned, the authentication method used and the source IP address of the access attempt.
Can SSH protocols be manipulated?+
In principle, yes, which is why a cross-check is carried out using independent sources such as wtmp, btmp and auditd logs.
Are key-based logins also logged?+
Yes, both password-based and key-based authentication attempts are logged, including the key fingerprint used.

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LanCologne – Linux Forensics Cologne

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

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