Automated Computer Forensics

We are developing a variety of techniques and tools for performing Automated Document and Media Exploitation (ADOMEX). The thrust of this research consists of several thrusts:

1. Developing open source tools for working with electronic evidence. This work is part of the AFF project.
2. Developing an unclassified Real Data Corpus (RDC) consisting of "real data from real people" that can be used to develop new algorithms and test automated tools.
3. Developing new algorithms and approaches for working in a "data-rich environment."

Recent Research Developments

File-based Forensics

• We have developed a batch analysis tool called system called fiwalk which can take a disk image and produce an XML file corresponding to all of the files, deleted files, orphan files, and all of the extracted file metadata from a disk image. This XML file can be used as an input to enable further automated media processing. Using this system we have created a variety of applications for reporting and manipulating disk images. We have also developed an efficient system for allowing remote file-level access of disk images using XML-RPC and REST. Details can be found in our paper Automating Disk Forensic Processing with SleuthKit, XML and Python, Fourth International IEEE Workshop on Systematic Approaches to Digital Forensic Engineering (IEEE/SADFE'09), May 2009.

• We have developed a prototype system for performing automated media forensic reporting. Based on PyFlag, the system performs an in-depth analysis of captured media, locates local and online identities, and presents summary information in a report that is tailed to be easy for the consumer of forensic intelligence. Details can be found in A Framework for Automated Digital Forensic Reporting, Lt. Paul Farrell, Master's Thesis, Naval Postgraduate School, Monterey, CA, March 2009

Bulk Data Forensics

We have developed a tool called frag_find which can report if sectors of a TARGET file are present on a disk image. This is useful in cases where a TARGET file has been stolen and you wish to establish that the file has been present on a subject's drive. If most of the TARGET file's sectors are found on the IMAGE drive---and if the sectors are in consecutive sector runs---then the chances are excellent that the file was once there. Frag_find performs this search using time-and-space efficient data structures arranged in multiple filtering layers. The program deals with the problem of non-unique blocks by looking for runs of matching blocks, rather than individual blocks. Frag_find is part of the NPS Bloom package, which can be downloaded from http://www.afflib.org.

Relevant Publications

• [http://simson.net/clips/academic/2009.SADFE.xml_forensics.pdf
• “Practical Applications of Bloom filters to the NIST RDS and hard drive triage,” Farrell, Garfinkel and White, ACSAC 2008
• "Carving Contiguous and Fragmented Files with Fast Object Validation", Garfinkel, S., Digital Investigation, Volume 4, Supplement 1, September 2007, Pages 2--12.
• "Complete Delete vs. Time Machine Computing," Garfinkel, S., Operating Systems Review, ACM Special Interest Group on Operating Systems, January 2007.
• "Forensic Feature Extraction and Cross-Drive Analysis," Garfinkel, S., Digital Investigation, Volume 3, Supplement 1, September 2006, Pages 71--81.
• "AFF: A New Format for Storing Hard Drive Images," Garfinkel, S., Communications of the ACM, February, 2006.
• "Standardizing Digital Evidence Storage," The Common Evidence Format Working Group (Carrier, B., Casey, E., Garfinkel, S., Kornblum, J., Hosmer, C., Rogers., M., and Turner., P.,) Communications of the ACM, February, 2006.