Digital forensic assurance after a major incident

Following a significant cyber security incident, a government agency faced the complex task of recovering from an extended network compromise while ensuring that threat actors had not left behind malicious artefacts, persistence mechanisms or compromised data within its environment. While incident response activities had identified and contained the immediate threat, substantial uncertainty remained regarding the integrity of large volumes of information stored across the agency’s systems.

Traditional cyber security and digital forensic approaches are typically focused on identifying malicious activity within active systems, executables and operating environments. In this case, however, the challenge extended far beyond active infrastructure. The agency needed to assess vast quantities of data at rest, including documents, archives and other business records, to determine whether they remained trustworthy, required remediation or posed an ongoing security risk. The scale of the data holdings and the complexity of the compromise meant that simply deleting information or rebuilding systems was neither practical nor desirable. The agency required a defensible, evidence-based process to identify residual threats while preserving critical information assets wherever possible.

ForenSys was engaged to design, implement and operate a large-scale digital forensic assurance program to support the agency’s recovery efforts. Drawing upon expertise in digital forensics, malware analysis, cyber security and forensic intelligence, ForenSys developed a bespoke methodology for assessing the integrity and risk profile of data across the affected environment.

Central to the approach was the development of a file-based risk assessment model that combined forensic artefact analysis, malware reverse engineering, metadata examination, behavioural indicators and threat intelligence to evaluate individual files and data holdings. Rather than relying solely on traditional malware detection techniques, the methodology enabled files to be dynamically assessed and categorised according to their level of risk.

This approach allowed the agency to make informed decisions regarding which data could be safely retained, which assets required cleansing or remediation, and which information should be quarantined or removed entirely. The forensic framework also enabled analysts to identify indicators of compromise and assess whether any active or residual threats remained within the environment.

The forensic assurance program provided the agency with a structured and defensible process for validating the integrity of its information holdings following the cyber incident. By applying forensic analysis and risk-based decision making at scale, the agency was able to preserve valuable business information while avoiding unnecessary destruction of data and costly remediation activities.

The project moved beyond traditional incident response and remediation by providing evidence-based assurance that the threat had been effectively removed from the environment. The resulting risk model enabled informed decision-making throughout the recovery process and provided senior stakeholders with confidence that retained information assets had been appropriately assessed and managed.

This engagement demonstrates ForenSys’ ability to apply digital forensics, cyber security and malware analysis in innovative ways to solve complex information assurance challenges. By combining forensic rigour with practical risk management, ForenSys helped the agency recover from a major cyber security incident while maintaining confidence in the integrity of its data and systems.