Anti-Analysis in an Office Document

Please note: This was a blog post I originally authored for Bromium. Due to changes in how they host their blog content, it has fallen into the archives and become somewhat difficult to find. I’m posting this content here mainly as an archive. Office documents have been a favorite method of distribution for malware authors for several years. While most malware authors go to great lengths to hide the intention of their macros through obfuscation, it is seldom that I’ve encountered macros that also exhibit anti-analysis techniques. I recently examined an office document that contained such capabilities. You can find…

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Identifying a User Form in an Office Document

In this post, we will be looking into ways to identify and analyze the presence of a user form in an office document. As I discussed in a previous post, user forms are often used to store resources needed by the malware author such as scripts (PowerShell, VBS), shellcode and strings. We will be using OLEDUMP to assist in our analysis and by the end of this post, you will be able to identify and trace the usage of user forms and their objects throughout macro code. For this analysis, we will be looking at the following malicious office document….

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Analyzing Malicious Office Documents with OLEDUMP

Microsoft office documents are a common vehicle used by malware authors to deliver malware. These documents, used for malicious purposes, are commonly referred to as maldocs. While there has been a variety of ways in which they have been used, one of the more prevalent is through the use of macros. Macros are written in Visual Basic for Applications (VBA), which is well documented on the Microsoft Developer Network (MSDN). This API allows malware authors to hook into life-cycle events of a document, such as AutoOpen, AutoClose and AutoExit (MSDN) in order to achieve code execution with minimal interaction from…

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First Pluralsight course now live!

I’m excited to announce that my first Pluralsight course Analyzing Malware for .NET and Java Binaries is now live! You can find the course at the following URL – http://www.pluralsight.com/courses/dotnet-java-binaries-analyzing-malware. The ability to quickly analyze software is a critical skill for anyone handling malware. This course will teach you techniques for reverse engineering Java and .NET binaries, how to generate indicators of compromise and get hands on with malware.

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Hack-in-the-Box Amsterdam 2018

Heading home from another great week at Hack-In-The-Box in Amsterdam. I had the opportunity to present on malicious office documents in the COMMSEC track, you can find my slides at the HITB site: https://conference.hitb.org/hitbsecconf2018ams/sessions/commsec-still-breaching-your-perimeter-a-deep-dive-into-malicious-documents/ or here https://0xevilc0de.com/cons/2018/hitb_ams/2018_HITB_AMS.pdf I’ll post the video when it’s available. Looking forward to next year!

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