A new Dharma ransomware variant has been developed that is currently evading detection by the majority of antivirus engines. According to Heimdal Security, the latest Dharma ransomware variant captured by its researchers was only detected as malware by one of the 53 AV engines on VirusTotal.
Dharma ransomware (also known as CrySiS) first appeared in 2006 and is still being developed. This year, several new Dharma ransomware variants have been released, each using new file extensions for encrypted files (.bip, .xxxxx, .like, java, .arrow, .gamma, .arena, .betta, and .tron to name but a few). In the past two months alone four new Dharma ransomware variants have been detected.
The threat actors behind Dharma ransomware have claimed many victims in recent months. Successful attacks have been reported recently by Altus Baytown Hospital in Texas, the Arran brewery in Scotland, and the port of San Diego.
While free decryptors for Dharma ransomware have been developed, the constant evolution of this ransomware threat rapidly renders these decryptors obsolete. Infection with the latest variants of the ransomware threat only give victims three options: pay a sizeable ransom to recover files, restore files from backups, or face permanent file loss.
The latter is not an option given the extent of files that are encrypted. Restoring files from backups is not always possible as Dharma ransomware can also encrypt backup files and can delete shadow copies. Payment of a ransom is not advised as there is no guarantee that files can or will be decrypted.
Protecting against ransomware attacks requires a combination of policies, procedures, and cybersecurity solutions. Dharma ransomware attacks are mostly conducted via two attack vectors: The exploitation of Remote Desktop protocol (RDP) and via email malspam campaigns.
The latest Dharma ransomware variant attacks involve an executable file being dropped by a .NET file and HTA file. Infections occur via RDP-enabled endpoints using brute force attempts to guess passwords. Once the password is obtained, the malicious payload is deployed.
While it is not exactly clear how the Arran brewery attack occurred, a phishing attack is suspected. Phishing emails had been received just before file encryption. “We cannot be 100 percent sure that this was the vector that infection occurred through, but the timing seems to be more than coincidental,” said Arran Brewery’s managing director Gerald Michaluk.
To protect against RDP attacks, RDP should be disabled unless it is absolutely necessary. If RDP is required, access should only be possible through a VPN and strong passwords should be set. Rate limiting on login attempts should be configured to block login attempts after a set number of failures.
Naturally, good backup policies are essential. They will ensure that file recovery is possible without payment of a ransom. Multiple copies of backups should be made with one copy stored securely off site.
To protect against email-based attacks, an advanced spam filter is required. Spam filters that rely on AV engines may not detect the latest ransomware variants. Advanced analyses of incoming messages are essential.
SpamTitan can improve protection for businesses through combination of two AV engines and predictive techniques to block new types of malware whose signatures have not yet been uploaded to AV engines.
For further information on SpamTitan and protecting your email gateway from ransomware attacks and other threats, speak to TitanHQ’s security experts today.