I received an email recently that referred to an older post in this blog regarding Prefetch file analysis. The sender mentioned that while doing research into Prefetch files, he'd run across this post (in Polish) that indicated that under certain circumstances, the run count in the Prefetch file "isn't precise". So, being curious, I ran the text of the site through Google Translate, and got the following (in part):
I did some small tests and it turns out that if the difference between the current date and the date last run stored in the. Pf is less than 2 minutes (120 seconds) it will not update the counter. Also, if any program (even malware) runs many times in a short period of time and we would like to know the date of the last of his starts, and the number - is on file in the folder Perfetch we can ride well.
Another interesting fact is that if you change the date (even using the watch in the address bar), we can easily cheat files. Pf. Assume that X was the last time the program was launched in July this year. Someone gained physical access to our computer and wants to run our named with letter X program. Of course would not want the contents of the Prefetch betrayed that there was an unauthorized launch. The method is trivial. The attacker changes the date (eg year 2002) and fires the program. The difference between 2002 and 2011 is less than 2 minutes (sounds weird, but subtract the smaller number of larger - we get a negative value). File. Pf remains unchanged, and the program X is seamlessly (from the standpoint of Perfetch) run.
If someone wants a really effective analysis, it appears that the files in the folder Perfetch rather not help him.
In short, what this says is that if someone runs an application several times in quick succession (i.e., 120 seconds, or 2 min), the Prefetch metadata isn't modified accordingly. Interesting stuff, and worth a further look, as if this is information that truly pans out and can be replicated, then it would likely have a significant impact on analysis and reporting. One thing I have thought about, however, is...does this happen? I mean, if a user launches Solitaire, what would be the purpose of launching it again within 2 min? What about malware? Let's say an intruder gains access to a system, and copies over some malware...what would be the purpose of launching it several times, within a 2 min period?
I've known for some time that various courses make use of my books, either as recommended reading or as required texts. For example, I understand from some recent emails that Utica College uses some of my books in their Cyber Security curriculum. As an author, this is pretty validating, and in a way, better than a review; rather than posting a review that says what's in the book, the instructors are actually recommending it or using it. Also, it's great marketing for the books.
Below is a recommendation for Windows Registry Forensics from Andy Spruill (Senior Director of Risk Management/FSO, GSI), posted here with his permission:
As an author, I usually sit back after a book has been out for a while and wonder if the information is of use to folks out there in the community; is the content of any benefit? I see the reviews posted to sites (Amazon, blogs, etc.) but many of them simply reiterate the table of contents without going into whether the reviewer found the information useful or not. I get sporadic emails from people saying that they liked the book, but don't often get much of a response when I ask what they liked about it. So when someone like Andy, with his background, experience, and credibility, uses and recommends the book, that's much better than a review. This isn't me suggesting to folks that it's a resource...after all, I'm the author, so what else am I going to say? It's someone like Andy...a practitioner and an instructor, teaching up-and-coming practitioners...saying that it's a resource that lends that statement credibility. So, a great big "thanks" to Andy, and to all of the other instructors, teachers, mentors, and practitioners out there who recommend books like WRF and DFwOST to their charges and colleagues.
I recently posted on Jump List and Sticky Notes analysis, and also released a Sticky Notes parsing tool. As of 11am, 31 Aug, there were just 10 downloads. One of the folks who downloaded the tool has apparently actually used it, and sent me an email...I received the following in that email from David Nides (quoted here with his permission):
Time after time I see examiners that aren't performing what I would consider comprehensive analysis because they don't go beyond push buttons forensics.
This is something I've mentioned time and again, using the term "Nintendo forensics". Chris Pogue also discusses this in his Sniper Forensics presentations. When developing the tools I wrote for parsing Jump Lists and Sticky Notes, I didn't find a great number of posts on the Interwebs from folks asking for assistance or how to parse these types of files...in fact, I really didn't find any. But I do know of folks are currently (and have been) analyzing Windows 7 systems; when doing so, do they understand the significance of Jump Lists and Sticky Notes, and are these artifacts being examined? Or is most of the analysis that's being done out there simply a matter of loading the acquired image into a commercial forensic analysis application and clicking a button?
What? Windows 8?!? We were just talking about Windows 7, and you've already moved on to Windows 8...and perhaps rightly so. It's coming folks...and I ran across this interesting post regarding improvements in the file operations (copy, move, etc.) experience. There are some interesting statistics described in the blog post, which were apparently derived from analysis of anonymous data provided by Windows 7 users (anyone remember Dr. W. Edwards Deming??). The post indicates that there's some significant tracking and optimization within the new version of Windows with respect to these file operations, and that users are granted a more granular level of control over these operations.
Okay, great...but in the words of Lon Solomon (who's a fantastic speaker, by the way...), "so what?" Well, if you remember when Windows XP came out, there was some trepidation amongst the DFIR community, with folks up in arms, screaming, "what is this new thing?!?"...yet over time, we've come to realize that for the sake of the "user eXPerience", there are significantly more artifacts for analysts. The same is true with Windows 7...so should we (DFIR analysts) expect anything less from Windows 8?
If you have had any thoughts or questions regarding the CDFS, or why you should join, here's another resource that provides an excellent view into answering that question. This is a timely post, considering this post that rehashes issues with accreditation and certification in the DFIR industry. Yes, I joined this week, and I'm looking forward to the opportunity to have a say in the direction of my chosen profession.
Imagine a vendor or software developer actually providing forensic artifacts...yeah, it's just like that! It seems that Google is doing us DFIR folks a favor and providing offline access to GMail. Looking at some of the reviews for the app, it doesn't look as if there's overwhelming enthusiasm for the idea, but this is definitely something to look for and take advantage of if you find it.