Digital forensics
Digital forensics is the methodical, evidentially sound identification, preservation, analysis and documentation of digital traces following a security incident, in order to reconstruct its course, scope and perpetrator in a court-admissible manner.
Digital forensics (also IT forensics) refers to the scientifically grounded examination of IT systems, storage media, networks and applications with the aim of preserving and evaluating the digital traces of an incident so that the findings hold up before authorities and courts. Unlike pure technical remediation, it follows a strict process model of identification, preservation (acquisition), analysis and documentation. The guiding principles are integrity (the evidence must not be altered), authenticity (its origin and genuineness can be proven) and an unbroken chain of custody, which logs every access to the evidence.
Methodologically, a distinction is drawn between post-mortem analysis (evaluation of powered-down systems and forensic disk images) and live forensics (capturing volatile data such as memory, open network connections or running processes). Core techniques include bit-exact imaging with hash verification (e.g. SHA-256), recovery of deleted files, evaluation of log data and timestamps (timeline analysis) and the examination of malware. In Germany, practice follows the BSI guide on IT forensics and the standard model for forensic investigations; internationally, ISO/IEC 27037 governs the identification, collection and preservation of digital evidence.
In a compliance context, digital forensics is closely interlocked with the incident response process and statutory reporting obligations. Under the NIS2 Directive and its German implementing law, essential and important entities must report security incidents within tight deadlines and maintain measures for handling and root-cause analysis; the GDPR likewise requires documented investigation of personal data breaches. Forensically clean preservation right at the start of an incident determines whether claims for damages, insurance cases, employment-law or criminal proceedings can later be pursued on a solid footing. Forensic readiness should therefore be anchored organisationally and technically before the emergency occurs.
Legal Basis
ISO/IEC 27037 (identification, collection and preservation of digital evidence); BSI IT forensics guide; Art. 21 and Art. 23 NIS2 Directive (EU) 2022/2555 in conjunction with national implementing law; Art. 33 GDPR (documentation of personal data breaches)
Practical Example
A mid-sized company discovers encrypted file shares and a ransom demand overnight. Instead of immediately rebuilding the affected servers, the incident response team isolates the systems from the network, captures the memory of the still-running machines and creates bit-exact images of the storage media with subsequent hash verification. Using timeline analysis of the logs, the digital forensics team reconstructs the initial access via a compromised VPN login, identifies the lateral movement and the volume of exfiltrated data. This evidentially sound documentation simultaneously serves the timely NIS2 report, the GDPR assessment of the data exfiltration and as the basis for the cyber insurance claim and possible criminal investigations.