A hack-for-hire group has been targeting organizations in the financial sector since 2012, for cyber-espionage purposes, Kaspersky’s security researchers reveal.
Dubbed DeathStalker, the “mercenary” advanced persistent threat (APT) has been targeting organizations worldwide, mainly focusing on law firms and financial entities. The adversary was observed quickly adapting to ensure the success of attacks, and to update their software at a fast pace.
Tracking the hacking group since 2018, Kaspersky was able to link its activity to the Powersing, Evilnum and Janicab malware families, thus suggesting that the threat actor might have been active since at least 2012, yet it continues to develop its toolset.
In recent attacks involving the PowerShell-based implant called Powersing, spear-phishing emails carrying an archive with a malicious LNK file inside were used as the initial vector. The shortcut files were designed to launch a convoluted sequence that ultimately results in arbitrary code being executed on the victim’s machine.
The Powersing implant was designed to periodically capture screenshots of the victim’s device and send them to the command and control (C&C) server, and to execute arbitrary PowerShell scripts received from the C&C. Providing a stealthy foothold onto the victim’s network, the implant allows attackers to install additional tools.
DeathStalker, Kaspersky reveals, used public services (including Google+, Imgur, Reddit, ShockChan, Tumblr, Twitter, YouTube, and WordPress) as dead drop resolvers, storing data via comments, descriptions, public posts, user profiles, and the like.
Powersing connects to these dead drop resolvers and retrieves the stored information, which is decoded and ultimately converted into an IP address that the malware uses to connect to the real C&C server. By following messages on dead drop resolvers, the researchers concluded that the malware has been in use since at least August 2017.
“Relying on well-known public services allows cybercriminals to blend initial backdoor communications into legitimate network traffic. It also limits what defenders can do to hinder their operations, as these platforms can’t generally be blacklisted at the company level, and getting content taken down from them can be a difficult and lengthy process,” Kaspersky notes.
The security researchers also identified a connection between the Powersing implant and the Janicab malware family, which was previously discussed publicly, with its oldest samples dating as far back as 2012.
The initial infection stages are identical for both malware families. Janicab uses YouTube as a dead drop resolver and packs features discovered in Powersing as well, and also employs network traffic similar to that of the more recent malware family. Moreover, the list of blacklisted VM MAC addresses is the same for both.
Evilnum is another malware family to use a LNK-based infection chain and fetch C&C information from a dead drop resolver (GitHub), as well as to capture screenshots that are sent to the C&C (albeit Evilnum has more capabilities than Powersing) and to focus on gathering business intelligence from its victims (which are from the fintech sector).
Kaspersky also identified a series of code overlaps between recent Evilnum samples and Janicab, which further suggests that the three malware families are related. The hackers took advantage of the COVID-19 pandemic in recent attacks to deliver both Janicab and Powersing.
DeathStalker’s victims are mainly from the financial sector and they include financial technology companies, law offices, wealth consultancy firms, and more. The threat actor was also observed targeting a diplomatic entity on one occasion.
Victim organizations, small to medium-sized businesses, are located in Argentina, China, Cyprus, India, Israel, Lebanon, Switzerland, Russia, Taiwan, Turkey, the United Kingdom and the United Arab Emirates. Victims are chosen either based on perceived value or based on customer requests.
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