To help malware analysts and security researchers overcome FinFisher’s advanced anti-disassembly obfuscation and virtualization features, ESET researchers have framed some clever tricks into a whitepaper, “ESET’s guide to deobfuscating and devirtualizing FinFisher”.
FinFisher, also known as FinSpy, has a history of being used in surveillance campaigns, both against legitimate targets and against political opposition in countries with oppressive regimes. Despite that, the latest thorough analyses dealt with samples from as long ago as 2010. Since then, FinFisher’s developers added strong anti-analysis measures; apparently, this is also the reason why subsequent reports about FinFisher don’t go into much technical detail. In one of the reports, a reputable security company even admitted that due to strong obfuscation, it was not possible to extract the C&C servers.
Having discovered a wave of surveillance campaigns in several countries in mid-2017, ESET researchers dug deep into the samples of FinFisher. To be able to start a thorough analysis of how these recent samples work, they first had to break through all of FinFisher’s protective layers.
“The company behind FinFisher has built a multimillion-dollar business around this spyware – so it comes as no surprise that they put a much bigger effort into hiding and obfuscation than most common cybercriminals. Our aim is to help our peers analyze FinFisher and thus protect internet users from this threat,” comments Filip Kafka, ESET malware analyst who leads the analysis of FinFisher.
Kafka expects the FinFisher creators to improve their protections to make FinFisher hard to analyze again. “With their huge resources, there is no doubt FinFisher will receive even better anti-analysis features. However, I expect their additional measures to cost more to implement while being easier to crack for us the next time around,” he says.
ESET’s research into FinFisher is ongoing. In the first stage, ESET researchers focused on the infection vector used in the mentioned campaigns. They strongly believe internet service providers have played the key role in infecting the victims with FinFisher.
Filip Kafka’s presentations of these findings along with a brief overview of FinFisher’s anti-analysis capabilities raised a lot of interest at the Virus Bulletin Conference as well as the AVAR conference in 2017.
Learn about latest ESET research into FinFisher: “ESET’s guide to deobfuscating and devirtualizing FinFisher”