The REvil (also known as Sodinokibi) is a Ransomware-as-a-Service (RaaS). The first attack of REvil was in middle of April 2019, and attracted huge attention span from the InfoSec world due to their uncanny similarities with GandCrab Ransomware. The group uses different distribution techniques of deploying ransomware such as exploit kits, scans and exploiting various vulnerable software (Oracle WebLogic), RDP servers, and backdoored software installers. Revil has made an estimated $100 million by infecting large business owners and they threaten to publish data if the ransom money is not paid by the victim.
The ransom note placed by REvil (Source: Elliptic)
Sodinokibi ransomware can encrypt data using curve25519/Salsa20 and keys using curve25519/AES-256-CTR. The user’s private key is encrypted by the malware using two public keys. Additionally, this infection uses asymmetric key scheduling and command and control server obfuscation, which enable the malware to function without a connection to the C2.