Jop Hofste graduates on identity ranking in digital evidence data

Scalable identity extraction and ranking in Tracks Inspector

by Jop Hofste

The digital forensic world deals with a growing amount of data which should be processed. In general, investigators do not have the time to manually analyze all the digital evidence to get a good picture of the suspect. Most of the time investigations contain multiple evidence units per case. This research shows the extraction and resolution of identities out of evidence data. Investigators are supported in their investigations by proposing the involved identities to them. These identities are extracted from multiple heterogeneous sources like system accounts, emails, documents, address books and communication items. Identity resolution is used to merge identities at case level when multiple evidence units are involved.

The functionality for extracting, resolving and ranking identities is implemented and tested in the forensic tool Tracks Inspector. The implementation in Tracks Inspector is tested on five datasets. The results of this are compared with two other forensic products, Clearwell and Trident, on the extent to which they support the identity functionality. Tracks Inspector delivers very promising results compared to these products, it extracts more or the same number of the relevant identities in their top 10 identities compared to Clearwell and Trident. Tracks Inspector delivers a high accuracy, compared to Clearwell it has a better precision and the recall is approximately equal what results from the tests.

The contribution of this research is to show a method for the extraction and ranking of identities in Tracks Inspector. In the digital forensic world it is a quite new approach, because no other software products support this kind of functionality. Investigations can now start by exploring the most relevant identities in a case. The nodes which are involved in an identity can be quickly recognized. This means that the evidence data can be filtered at an early-stage.

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