A Sygnia report revealed that two separate threat groups linked to China, Night Sky and Cheerscrypt, have begun working together. The outlined attacks targeted Windows and VMWare ESXi environments and emanated from a threat actor now dubbed Emperor Dragonfly. Itay Shohat, director of incident response and threat hunting at Sygnia, said these threat actors are also launching attacks by leveraging the Log4Shell vulnerability discovered last year. In one attack, threat actors compromised a VMware Horizon server using the Log4Shell vulnerability, which then allowed them to move laterally by executing code remotely and deploying Cobalt Strike Beacons. After a dwell time of several months, the threat actors used the Rclone open-source command line tool to exfiltrate sensitive information to a cloud storage service before installing a Cheerscrypt ransomware payload. Although Cheerscrypt is considered a Linux-based ransomware family that targets ESXi servers, Sygnia researchers found this malware also installed on Windows servers. Emperor Dragonfly, also known as DEV-0401/ BRONZESTARLIGHT, does not operate in an affiliate model and refrains from purchasing initial access from other threat actors, the researchers found. Rather, the group manages all stages of the attack life cycle on its own. The group also rebrands their ransomware payloads every few months, which helps them stay under the radar, unlike other notorious groups which act to build up their reputations.
By Anthony Zampino Introduction Leading up to the most recent Russian invasion of Ukraine in