The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has published an analysis of the FiveHands ransomware, roughly one week after FireEye’s Mandiant security researchers reported seeing the malware in recent attacks.
Written in C++, the FiveHands ransomware appears to be the successor of DeathRansom, based on code similarities between the two. However, both families also show a connection to the HelloKitty ransomware.
The malware is employed by a financially motivated threat actor known as UNC2447, which has been actively targeting various organizations in Europe and North America, and which has shown advanced capabilities.
This week, CISA revealed that it received a total of 18 malicious files associated with a FiveHands attack, including eight open-source penetration testing and exploitation tools, the ransomware itself, and nine files associated with the SombRAT remote access Trojan (RAT).
As part of the attack, which managed to successfully compromise an organization, the adversary leveraged those legitimate and malicious tools to steal data, encrypt files, and demand a ransom payment from the victim organization.
A security flaw in a virtual private network (VPN) product was exploited as the initial attack vector, with publicly available tools then used for network discovery and the ransomware executed at a later stage of the attack.
FiveHands, CISA notes, uses a public key encryption scheme called NTRUEncrypt, and enumerates then erases Volume Shadow copies to prevent data recovery. As part of the attack, SombRAT was also deployed, to facilitate the download and execution of additional malicious payloads.
In its malware analysis report (MAR) and accompanying analysis report (AR), CISA provides not only detailed technical information on the malware itself, but also recommendations on how organizations can mitigate similar attacks.
Last week, the Institute for Security and Technology (IST) published a set of 48 recommendations to combat ransomware, roughly two months after the National Cyber Investigative Joint Task Force (NCIJTF) published a joint-sealed ransomware factsheet that contains information on attack techniques and prevention methods.
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