Rewterz Threat Alert – DJVU Ransomware – Active IOCs

Severity

High

Analysis Summary

DJVU was one of the most active and widespread versions of ransomware in 2019. DJVU was first used aggressively in campaigns in 2019, even though it had been around for about a year. Continuously changing its extensions and payloads has helped it evade detection. Its encryption techniques also continue to improve. Earlier versions of the malware, where the key was not generated by its command and control servers, were easier to recover the files. In current versions, decryption is more difficult. Delivery of the malware has been through cracked programs, keygens, activators, fake setup programs, and fake Windows updates. To avoid infecting victims in specific countries, DJVU did not use local information, such as keyboard layouts and timezone settings, but rather it uses the information returned by a request sent to https[:]//api.2ip.ua/geo.json. Persistence is achieved through a scheduled task. The MAC address of the ethernet card is used as the basis of a unique identifier for the system. This identifier is sent to DJVU’s command and control server when then returns an RSA-2048 public key to be used in the encryption. Additional malware is then downloaded and installed, including an information stealer called Vidar.

Impact

• Information Theft
• File Encryption

Indicators of Compromise

MD5

• cb322a651accb8be3265ce7c85302dee

SHA-256

• 96604322a087557a506b603f023ccf61545eb779ec899b98f579a0c4803ea13f

SHA-1

• 9d9095e0ac04393b1549c3d3285e8b1709549c2e

Remediation

• Block all threat indicators at your respective controls.
• Search for IOCs in your environment.
• Always be suspicious about emails sent by unknown senders.
• Never click on the links/attachments sent by unknown senders.