On June 27, 2017, multiple organizations – many in Europe – reported significant disruptions they are attributing to Petya ransomware. Based on initial information, this variant of the Petya ransomware may be spreading via the EternalBlue exploit used in the WannaCry attack from last month.
Trusted sources and open-source reporting have suggested that the initial infection vector for this campaign was a poisoned update for the MeDoc software suite, a software package used by many Ukrainian organizations. The timing of a MeDoc software update, which occurred on June 27, is consistent with initial reporting of the ransomware attack, and the timing correlates to lateral movement via PSExec we observed in victim networks starting around 10:12 UTC. Additionally, the MeDoc website currently displays a warning message in Russian stating: "On our servers is occurring a virus attack. Our apologies for the temporary inconvenience!"
Our initial analysis of the artifacts and network traffic at victim networks indicate that a modified version of the EternalBlue SMB exploit was used, at least in part, to spread laterally along with WMI commands, MimiKatz, and PSExec to propagate other systems. Analysis of the artifacts associated with this campaign is still ongoing and we will update this blog as new information come available.
FireEye has confirmed the following two samples related to this attack:
FireEye has mobilized a Community Protection Event and is continuing to investigate these reports and the threat activity involved in these disruptive incidents. FireEye as a Service (FaaS) is actively engaged in monitoring customer environments.
While FireEye detection leverages behavioral analysis of malicious techniques, our team has created a YARA rule to assist organizations in retroactively searching their environments for this malware, as well as detecting future activity. Our team has focused on the malicious attacker techniques that are core to the operation of the malware: SMB drive usage, ransom demand language, the underlying functions and APIs, and the system utilities used for lateral movement. The thresholds can be modified in the condition section that follows.
// FUNCTIONALITY, APIS
FireEye has read reports that the malware is spread by an email lure containing a malicious Office document attachment or links to infected documents exploiting CVE-2017-0199. We are confident that this document is unrelated to the current outbreak of activity, and we have seen no other indicators that CVE-2017-0199 is related. While FireEye detects these campaigns, we have not observed any correlation with known victims of the Petya attacks.
This activity highlights the importance of organizations securing their systems against the EternalBlue exploit and ransomware infections. Microsoft has provided a guide for securing Windows systems against the EternalBlue exploit in the context of the WannaCry ransomware. A robust back-up strategy, network segmentation and air gapping where appropriate, and other defenses against ransomware can help organizations defend against ransomware distribution operations and quickly remediate infections.