GREM Achievement Unlocked

I had been going through the SANS FOR610 Reverse Engineering Malware content OnDemand recently and last week I knocked out the GREM. I figured it would be a good time to post a few thoughts on it and talk about a few things that people can do to help prep for the course.

This was the first time in a while where I prepped for a GIAC exam without attending the course live. I was a bit worried about that with such a technical course but I ended up having a great experience. This was also the first time one of my courses has had the new style of OnDemand where the course was recorded in a professional studio instead of during a live class. The results were really nice and felt for intimate than I expected.

Every time a lab came up I would pause the course, work through the lab and then watch Lenny Zeltser’s walkthrough afterwards. He did a fantastic job of explaining things and going through the labs step by step. Even with dealing with advanced concepts, I never felt lost.

In a stroke of great timing, when I was about 75% through the course content I got a spear fishing email at work with an attachment. I checked it against virustotal.com and only 4/56 flagged it as malicious and there was no further information. I thought it would be a good chance to put my newly found skills to the test and examine the attachment. I fired up my two VMs and in a short amount of time I had a clear picture on what the malware was doing, had network based and host based IOCs and was walking through the code in a debugger examining how it was unpacking itself. It was great practice and a nice confirmation that what I had learned worked in the real world.

In prepping for the exam I had spoken to several friends who held the GREM certification. One of the biggest things someone can do to help prepare for the course is to get comfortable with assembly language and being able to watch/understand what the stack is doing within a debugger. The course teaches these things but if you’ve already been exposed to them you’ll feel a lot more comfortable and it will allow you to focus on learning other material.

Different people have different learning styles but this is one area where I think it’s really beneficial to watch someone walking through examples while they explain what’s going on. A fantastic free resource for getting exposed to Assembly Language is Vivek Ramachandran’s “Assembly Language Megaprimer for Linux” 11 part video series at SecurityTube.net (http://www.securitytube.net/groups?operation=view&groupId=5) or on YouTube (https://www.youtube.com/watch?v=K0g-twyhmQ4&list=PL6brsSrstzga43kcZRn6nbSi_GeXoZQhR). Vivek also has a cheap but not free “x86 Assembly Language and Shellcoding on Linux” series at PentesterAcademy.com which really helped me prepare for working on both Reverse Engineering and Exploit Development.

Overall I thought the FOR610 was a fantastic course and I got exactly what I wanted to get out of it.

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