Forensic tools and modern challenges: encryption, cloud, volume and anti-forensics

Tools by category

Free tools such as Autopsy, Volatility and Wireshark are excellent for learning in a lab and are used professionally too. Tools speed up the work, but the examiner is responsible for the conclusions. Knowing what a tool does underneath, for example how it decides a file was deleted, lets you explain and defend its output.

The big challenges

• Encryption: full-disk encryption such as BitLocker and FileVault, and encrypted phones, mean a seized device may be unreadable without keys. Recovery keys stored in company directories or captured from memory on a running machine can help.
• Cloud: evidence sits with providers in other countries, often available only as logs with limited retention. Turning on and keeping audit logs before an incident is vital.
• Volume: a single case may involve several terabytes. Triage and targeted collection help examiners focus on what matters.
• Anti-forensics: attempts to hide or destroy evidence (see below).
• Tool trust: results must be reliable, so labs test tools against known data sets and record versions.

Anti-forensics and how examiners respond

Attackers and some insiders try to make investigation harder. Common techniques include clearing event logs, wiping files with secure deletion tools, changing file timestamps (timestomping), hiding data in unusual places and running code only in memory. These attempts often leave traces of their own. A cleared Windows security log records an event saying it was cleared. Changed timestamps may disagree with other artefacts such as the file system journal. Wiping tools leave signs that they ran. Defenders can also make anti-forensics less effective by sending logs to a central system in real time, so local tampering does not remove the only copy.

Validating tools and methods

If a finding is challenged, you must show your method is sound. Good practice is to test tools on reference data sets with known contents, check important findings with a second tool, and record tool names, versions and settings. Some jurisdictions expect forensic labs to work to quality standards such as ISO/IEC 17025.

Real-world example: a wiped laptop

At a fictional design studio, a manager suspects an employee of deleting project files before leaving. The examiner images the laptop and finds that a free file-wiping tool was installed and run the day before the employee resigned, and that the Windows security log had been cleared. Neither the deleted files nor the cleared log could be recovered, but the log-cleared event, the wiping tool's artefacts and cloud storage audit logs together showed what happened and when. The studio restored its files from cloud version history and used the findings in its disciplinary process.