IT Forensics · Linux

Forensic analysis of the DNS cache and resolver configuration – using name resolution as a forensic lead

DNS resolver configurations determine which Server a system uses for name resolution, whilst a locally maintained DNS cache may, in some circumstances, allow inferences to be drawn about previously resolved domain names.

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Not every Linux system maintains a persistent local DNS cache, which is why its availability must be checked on a case-by-case basis before any forensic conclusions can be drawn.

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 check the resolver configuration and any local DNS cache that may be present, and analyse these in conjunction with other network artefacts in order to classify the domains contacted.

Typical areas of application

Reconstruction of registered domain names
Investigation of command-and-control communication via DNS
Assessment of manipulated resolver configurations
Supplementing network traffic analyses
Incident Response on Linux Systems
Judicial and non-judicial expert reports

How a DNA analysis is carried out

Once the backup has been completed, the active resolver configuration is first analysed to determine which DNS-Server servers are actually in use. If a local cache is present and can be analysed, the domain resolutions it contains are extracted and correlated with other network and process artefacts.

Why is DNA analysis relevant in forensic science?

Domain names that have been contacted can provide valuable insights into a system’s actual communications, for example when identifying command-and-control infrastructure as part of a malware investigation.

A tampered resolver configuration – for example, one designed to redirect traffic to a malicious DNS server (Server) – may also itself be the subject of a forensic investigation.

Frequently Asked Questions

Does every Linux system store a DNS cache?+
Not necessarily; this depends on the resolver software used and the system configuration.
Can the resolver configuration be tampered with?+
Yes, for example, to redirect requests specifically to a monitored DNS-Server, which is subject to forensic examination.
Is the DNS cache sufficient for a complete reconstruction of the communication?+
Not usually; it is used as a supplementary source alongside other network artefacts.

LanCologne – Linux Forensics Cologne

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

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