Eset’s Guide to DeObfuscating and DeVirtualizing FinFisher

Eset’s Guide to DeObfuscating and DeVirtualizing FinFisher

From the introduction:

Thanks to its strong anti-analysis measures, the FinFisher spyware has gone largely unexplored. Despite being a prominent surveillance tool, only partial analyses have been published on its more recent samples.

Things were put in motion in the summer of 2017 with ESET’s analysis of FinFisher surveillance campaigns that ESET had discovered in several countries. In the course of our research, we have identified campaigns where internet service providers most probably played the key role in compromising the victims with FinFisher.

When we started thoroughly analyzing this malware, the main part of our effort was overcoming FinFisher’s anti-analysis measures in its Windows versions. The combination of advanced obfuscation techniques and proprietary virtualization makes FinFisher very hard to de-cloak.

To share what we learnt in de-cloaking this malware, we have created this guide to help others take a peek inside FinFisher and analyze it. Apart from offering practical insight into analyzing FinFisher’s virtual machine, the guide can also help readers to understand virtual machine protection in general – that is, proprietary virtual machines found inside a binary and used for software protection. We will not be discussing virtual machines used in interpreted programming languages to provide compatibility across various platforms, such as the Java VM.

We have also analyzed Android versions of FinFisher, whose protection mechanism is based on an open source LLVM obfuscator. It is not as sophisticated or interesting as the protection mechanism used in the Windows versions, thus we will not be discussing it in this guide.

Hopefully, experts from security researchers to malware analysts will make use of this guide to better understand FinFisher’s tools and tactics, and to protect their customers against this omnipotent security and privacy threat.

Beyond me at the moment but one should always try to learn from the very best. Making note of what can’t be understood/used today in hopes of revisiting it in the future.

Numerous reports describe FinFisher as spyware sold exclusively to governments and their agencies. Perhaps less “exclusively” than previously thought.

In any event, FinFisher is reported to be in the wild so perhaps governments that bought Finfisher will be uncovered by FinFisher.

A more deserving group of people is hard to imagine.

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