Notes on Vista forensics
Part two: Digesting the differences
In part one of this series we looked at the different editions of Vista available and discussed the various encryption and backup features which might be of interest to forensic examiners.
In this article we will look at the user and system features of Vista which may (or may not) present new challenges for investigators and discuss the use of Vista itself as a platform for forensic analysis.
User files and applications
One of the first things to note about users' data files is that they're not where they used to be! Instead of the familiar "Documents and Settings" folder we must instead look to a new folder called "Users". Other folders which typically fall under the scope of an examination have also moved so examiners running scripts which expect certain files or folders to be in specific locations may need to do some editing. Another interesting change is that Vista is configured by default to not update the last access time on files, a decision made to increase file system performance.
At the application level, much forensic work consists of reconstructing web browsing and email activity, so let's take a look at the relevant programs provided by Vista.
Vista ships with Windows Internet Explorer 7 for web browsing and, although forensic examiners will certainly encounter other browsers during Vista's lifetime, it seems reasonable to assume that IE7 and its Microsoft successors will represent the vast majority of browsers whose use comes under investigation. Familiarity with IE's usage of files and directories, together with experience using appropriate tools for recreating browsing activity (using the browser history, cache, cookies, favorites, etc), will continue to be essential components of every investigator's arsenal and most people currently working in the field will already be familiar with IE7 since its release last year. The version of IE7 included with Vista does include a number of additional features, however, which examiners should at least be aware of (such as Protected Mode, Parental Controls, and enhanced Network Diagnostics).
Windows Mail is the standard, standalone email client included with Vista. Functionally, if not aesthetically, similar to Outlook Express, Windows Mail is likely to be the focus of many investigations.
In terms of architecture, however, it should be noted that Windows Mail uses a JET database and messages, including newsgroup posts, are now stored in individual files (mail files have a .eml extension and newsgroup posts .nws).
These files have two "streams" - for mail messages the first stream consists of RFC compliant MIME data and the second stream holds XML metadata. Another change is that account information which used to be stored in the Registry is now also held in XML format within the Windows Mail folder of a user's profile.
However, Windows Mail is not the only email option likely to be available to Vista users at some stage in the future. Windows Live Mail Desktop, somewhat unfortunately abbreviated to "WLMd", is an email solution currently in beta which Microsoft describes as "an email client that can be downloaded onto Windows XP or Windows Vista...a rough super-set of Windows Mail in Windows Vista".
While the exact set of features is still being worked out, in broad terms this is an email client which will integrate with Windows Live Hotmail (previously known as Windows Live Mail), Microsoft's Web 2.0 mail client, and include a number of other features above and beyond those available in Windows Mail. Investigators already familiar with cases involving Hotmail usage will probably be well prepared for the challenges arising from WLMd but it will be interesting to see exactly what those challenges are once this client is released - those wishing to get a head start may wish to check out the beta.
In fact, situations where a user's data may no longer be stored on the local machine should come as no surprise to forensic examiners. Over the past few years most practitioners have come to realize that the hard disk is not the only source of potential evidence and have been forced to take a more holistic view of a suspect's computing environment whether that means a focus on the nearby, such as RAM or backup storage, or further afield, such as network devices or remote servers.