Past Selected Articles
Archived past selected research articles
2008-Oct-30 Semi-Supervised Named Entity Recognition: Learning to Recognize 100 Entity Types with Little Supervision, David Nadeau, PhD Thesis, University of Ottawa, 2007.
- Named Entity Recognition is the process of analyzing text documents and automatically identifying the Who, What, Where and Whens. David Nadeau's thesis presents a novel approach which bootstraps a named entity recognizer using semi-structured documents on the web. Few forensic tools use NER today, but that may well change in the future. What makes this thesis so interesting to read is that it also has a history of the last 20 years or so of the field. Highly recommended.
2008-Oct-24 Advanced JPEG carving, Michael I. Cohen, Proceedings of the 1st international conference on Forensic applications and techniques in telecommunications, information, and multimedia and workshop
Michael I. Cohen presents a fully automated carver which can carve fragmented JPEGs using typical fragmentation patterns. (Cohen argues the the DFRWS carving challenges do not represent typical fragmentation patterns.)
- Threats to Privacy in the Forensic Analysis of Database Systems
- Patrick Stahlberg, Gerome Miklau, and Brian Neil Levine
- Proceedings of the 2007 ACM SIGMOD international conference on Management of data table of contents
Beijing, China. This paper looks at residual data left behind in databases after DELETE, UPDATE, and VACUUM operations. The authors show that residual data is a real issue in databases, and that it's pretty easy to modify a database so that no residual data is left behind. MySQL with MyISM tables has clean delete, but InnoDB does not. Very much worth reading.
- Lest We Remember: Cold Boot Attacks on Encryption Keys
- J. Alex Halderman, Princeton University; Seth D. Schoen, Electronic Frontier Foundation; Nadia Heninger and William Clarkson, Princeton University; William Paul, Wind River Systems; Joseph A. Calandrino and Ariel J. Feldman, Princeton University; Jacob Appelbaum; Edward W. Felten, Princeton University
- USENIX Security '08 Refereed Paper
- Awarded Best Student Paper
- Increasingly memory analysis is of interest in forensic research---both because new malware only resides in memory, and because memory analysis is frequently the only way for analysts to get the keys that are used to protect cryptographic file systems. In this paper the authors show that cryptographic keys in memory are vulnerable to exploitation after the computer is turned off. The authors show that the contents of dynamic RAM are retained seconds, and sometimes minutes, after power is turned off. By chilling the memory the data can be retained as long as necessary. And while most laptops wipe their memory when they reboot, the authors show that the chilled memory can be moved from one laptop that wipes to another laptop that does not wipe. Finally, the authors show that it is possible to find the cryptographic keys in memory and correct random bit errors by using the AES key schedule as an error-correction code. The authors demonstrate an attack USB stick which reboots a computer protected with BitLocker, finds the cryptographic keys, and then allows access to the cleartext information on the disk.
2008-July-27 The Symposium on Usable Privacy and Security (2008) concluded this past week in Pittsburgh, PA. One paper that appeared which is interesting to the network forensics crowd is The Challenges of Using an Intrusion Detection System: Is It Worth the Effort?, by Rodrigo Werlinger, Kirstie Hawkey, Kasia Muldner, Pooya Jaferian and Konstantin Beznosov. slides
In this article, the authors conducted interviews with 9 IT security practitioners who have worked with IDSs performed ethnographic observations within an organization that was deploying a new IDS. They found that security practitioners were heavily divided on the value of the IDS, and learned that the an IDS really only generates value if the network is well-understood before the IDS is deployed.
The current Fall 2007 issue has an interesting article Mobile Phone Forensics Tool Testing: A Database Drive Approach by Baggili, Mislan, and Rogers at Purdue University. Given that phones are increasingly a primary source of forensic information in many cases, we need to be sure that the tools that are used for forensic analysis present data that is accurate and repeatable. Unfortunately they frequently aren't because of there are so many different kinds of phones on the market and the forensic tools lag far behind the market.
Ibrahim M. Baggili, Richard Mislan, Marcus Rogers -
- International Journal of Digital Evidence 6,2007
BibtexAuthor : Ibrahim M. Baggili, Richard Mislan, Marcus Rogers
In : International Journal of Digital Evidence -
Date : 2007
Anandabrata Pal, Taha Sencar, Nasir Memon - Detecting File Fragmentation Point Using Sequential Hypothesis Testing
BibtexAuthor : Anandabrata Pal, Taha Sencar, Nasir Memon
Title : Detecting File Fragmentation Point Using Sequential Hypothesis Testing
In : -
Date : 2008
This DFRWS 2008 article presents an improved approach for carving fragmented JPEGs using sequential hypothesis testing. According to the authors, "The technique begins with a header block identifying the start of a ﬁle and then attempts to validate via SHT each subsequent block following the header block. The fragmentation point is identiﬁed when SHT identiﬁes a block as not belonging to the ﬁle. By utilizing this technique, we are able to correctly and efﬁciently recover JPEG images from the DFRWS 2006  and 2007  test sets even in the presence of tens of thousands of blocks and ﬁles fragmented into 3 or more parts. The bifragment gap carving technique enhanced with SHT allows us to improve the performance result of DFRWS 2006 challenge test-sets, although the technique cannot be used for DFRWS 2007. We then show how Parallel Unique Path enhanced with SHT is able to recover all fragmented JPEGs from DFRWS 2006 and all recoverable JPEGs from 2007 challenge test-sets. As far as we are aware, no other automated technique can recover multi-fragmented JPEGs from the DFRWS 2007 test set."
Yoginder Singh Dandass, Nathan Joseph Necaise, Sherry Reede Thomas - An Empirical Analysis of Disk Sector Hashes for Data Carving
- Journal of Digital Forensic Practice 2:95--106,2008
BibtexAuthor : Yoginder Singh Dandass, Nathan Joseph Necaise, Sherry Reede Thomas
Title : An Empirical Analysis of Disk Sector Hashes for Data Carving
In : Journal of Digital Forensic Practice -
Date : 2008
Authors Dandass et. al analyzed 528 million sectors from 433,630 unique files. They computed the CRC32, CRC64, MD5 and SHA-1 of each sector. Not surprisingly, they find that the MD5 and SHA-1s of the sectors are different if the sectors are different. They find 94 CRC64 collisions and 30 million CRC32 collisions. The conclusion is that, if you are search for a single sector or building a database of single sector hashes, you are better off building a database of CRC64s because they are easier to store and dramatically faster to calculate than the traditional hash functions, and they are nearly as accurate.