Thumbnail images can be extracted from a variety of sources in a given piece of evidence under investigation (e.g., cached browser images, thumbs.db files, embedded JPEGs, etc.). In OS X, there is a relatively under-exploited source of thumbnails generated from Quick Look technology. In this post, we’ll explore how this particular artifact can be exposed and understood in your next OS X investigation.
To preface this post, many artifacts created in OS X are most easily reviewed and understood on a Mac natively. However, many investigators lack access to a Mac for forensic investigation. If you haven’t used EnCase for OS X investigations, you may not be aware EnCase has been continuously adding support for investigation of OS X systems, including the comprehensive support for HFS+ extended attributes, Plist parsing, an automated OS X artifact processing module, as well as most recently, native support for decryption of OS X keychains. With each release of EnCase, there are fewer techniques that remain best-suited or unique to a native OS X toolset. That being said… let’s get on with it!