File Format Identification

File Format Identification is the process of figuring out the format of a sequence of bytes. Operating systems typically do this by file extension or by embedded MIME information. Forensic applications need to identify file types by content.

Tools

libmagic

• Written in C.
• Rules in /usr/share/file/magic and compiled at runtime.
• Powers the Unix “file” command, but you can also call the library directly from a C program.
• http://sourceforge.net/projects/libmagic

DROID

• Writen in Java
• Developed by National Archives of the United Kingdom.
• http://droid.sourceforge.net

TrID

• XML config file
• Closed source; free for non-commercial use
• http://mark0.net/soft-trid-e.html

Stellent/Oracle Outside-In

• Proprietary but free demo.
• http://www.oracle.com/technology/products/content-management/oit/oit_all.html

Bibliography

Current research papers on the file format identification problem. Most of these papers concern themselves with identifying file format of a few file sectors, rather than an entire file.

Predicting the Types of File Fragments, William Calhoun, Drue Coles, DFRWS 2008 [slides]

File type identification of data fragments by their binary structure. , Karresand Martin, Shahmehri Nahid. Proceedings of the IEEE workshop on information assurance; 2006b. p. 140–7. [slides]

Fileprints: identifying file types by n-gram analysis, LiWei-Jen, Wang Ke, Stolfo SJ, Herzog B.., IProceeding of the 2005 IEEEworkshop

on information assurance; 2005 [slides]