DeathStalker cyber-mercenary group targets the financial sector

A hack-for-hire group, tracked as DeathStalker, has been targeting organizations in the financial sector since 2012 Kaspersky researchers say.

DeathStalker is a hack-for-hire group discovered by Kaspersky, it has been targeting organizations worldwide, mainly law firms and financial entities, since 2012. Victim organizations are small and medium-sized businesses located in Argentina, China, Cyprus, India, Israel, Lebanon, Switzerland, Russia, Taiwan, Turkey, the United Kingdom and the United Arab Emirates.

The APT group rapidly evolved its tactics to compromise the target organization.

“DeathStalker: a unique threat group that appears to target law firms and companies in the financial sector. As far as we can tell, this actor isn’t motivated by financial gain. They don’t deploy ransomware, steal payment information to resell it, or engage in any type of activity commonly associated with the cybercrime underworld.” reads the post published by Kaspersky. “Their interest in gathering sensitive business information leads us to believe that DeathStalker is a group of mercenaries offering hacking-for-hire services, or acting as some sort of information broker in financial circles.”

The experts are monitoring the group’s activities since 2018, the group employed numerous strains of malware, including linked them to Powersing, Evilnum, and Janicab malware families. Kaspersky speculates the adversary group might have been active since at least 2012.

In recent attacks, DeathStalker mercenaries employed the PowerShell-based implant Powersing, the attackers used spear-phishing messages with an archive containing a malicious LNK file.

Upon clicking on the shortcuts, the execution of a convoluted sequence resulted in the execution of arbitrary code on the victim’s machine. 

Powersing allows the attacker to periodically sends screenshot captures to the C2, and to execute arbitrary PowerShell scripts received from the C&C. The malicious code also allows threat actors to install additional tools.

DeathStalker leveraged multiple public services (including Google+, Imgur, Reddit, ShockChan, Tumblr, Twitter, YouTube, and WordPress) as dead drop resolvers, using them to store data via comments, descriptions, public posts, user profiles, and the like.

“The DeathStalkers toolchain leverages a number of public services as dead drop resolvers. These services provide a way for attackers to store data at a fixed URL through public posts, comments, user profiles, content descriptions, etc. Messages left by the attackers follow the following patterns: “My keyboard doesn’t work… [string].” and “Yo bro I sing [Base64 encoded string] yeah”.” continues the report.

Powersing connects the drop resolvers to retrieve the stored information, decode it, and ultimately convert into an IP address that the malware uses to connect to the real C&C server. The analysis of the messages on dead drop resolvers revealed that the implant has been in use since at least August 2017.

The use of trusted public services allows threat actors to hide backdoor communications into legitimate network traffic. Experts also linked the Powersing implant to the Janicab malware family, which was first spotted in 2012.

The two families of malware share the infection stages and the list of the list blacklisted VM MAC addresses.

Janicab uses YouTube as a dead drop resolver and includes features discovered in Powersing.

Evilnum is another malware family first spotted by ESET researchers in 2018, it uses a LNK-based infection chain and GitHub as a dead drop resolver. While Evilnum provides more capabilities than Powersing, it is also able to capture screenshots.

The researchers also discovered that Evilnum samples and Janicab also share portions of the code, the above findings suggest that the three malware families are related.

DeathStalker attackers recently exploited COVID-19 as lure to spread both Janicab and Powersing implants.

Researchers believe that the group is still developing new tools for its arsenal.

The hackers took advantage of the COVID-19 pandemic in recent attacks to deliver both Janicab and Powersing.

“Due to its ongoing operations (DeathStalker notably leveraged COVID-19 for both Janicab and Powersing implant deployment since March 2020) and continuous activity since 2018, we believe that DeathStalker is still developing its toolset, and that we’ll have more to report on in the near future.” concludes the report.

Pierluigi Paganini

(SecurityAffairs – hacking, DeathStalker)