Malware Analysis Tools

While it is a lot of fun to parse structures from a hex dump or disassemble opcodes in my head, I rely on many tools to reverse engineer software efficiently. In general, it does not matter which tools you use. It only matters that you know how to use them. However, finding the right tool for the task at hand is not always easy.

Below is a non-exhaustive list of tools I use regularly during malware analysis. Many of these tools have been recommended to me by very talented and experienced colleagues. Others I found while reading blogs or malware analysis reports. I hope this list inspires you to incorporate some of these tools into your analysis process.

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IDA Pro Anti-Disassembly, Basic Blocks, and IDAPython

In this blog post I am going to discuss how you can interact with basic blocks in IDAPython. Before we jump into the technical details, I want to provide some context and show why I became interested in exploring this feature of IDA Pro.

Background and Motivation

The other day I reverse engineered a backdoor that was heavily armored with two classic anti-disassembly techniques. The first technique substitutes jmp instructions with sequences of push and retn instructions. Figure 1 shows how this hinders the program’s control flow analysis. First, IDA Pro interprets the retn instruction to mark a function’s end. Second, IDA Pro is not able to identify the target addresses as code and hence does not disassemble them.

.text:00564A90 sub_564A90      proc near               ; CODE XREF: ___tmainCRTStartup+10Dp
.text:00564A90                 push    564C87h
.text:00564A95                 retn
.text:00564A95 sub_564A90      endp
Figure 1

Figure 2 shows the same disassembly after I changed the push operand type to offset.

.text:00564A90 sub_564A90      proc near               ; CODE XREF: ___tmainCRTStartup+10Dp
.text:00564A90                 push    (offset loc_564C83+4)
.text:00564A95                 retn
.text:00564A95 sub_564A90      endp
Figure 2

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Moin Welt!

O Tannenbaum! The year is almost over and my first blog post is here. Publishing some original content has been one of my goals for 2016. So, I am very excited that it is finally happening.

In 2017, I will post at least once a month. Really, I already have a list of topics…

Happy Holidays and an awesome New Year!

O Tannenbaum!