Microsoft Threat Intelligence Center (MSTIC) has uncovered a wide-scale malicious email campaign operated by NOBELIUM, the threat actor behind the attacks against SolarWinds, the SUNBURST backdoor, TEARDROP malware, GoldMax malware, and other related components. The campaign, initially observed and tracked by Microsoft since January 2021, evolved over a series of waves demonstrating significant experimentation. On May 25, 2021, the campaign escalated as NOBELIUM leveraged the legitimate mass-mailing service, Constant Contact, to masquerade as a US-based development organization and distribute malicious URLs to a wide variety of organizations and industry verticals.
Microsoft is issuing this alert and new security research regarding this sophisticated email-based campaign that NOBELIUM has been operating to help the industry understand and protect from this latest activity. Below, we have outlined attacker motives, malicious behavior, and best practices to protect against this attack. You can also find more information on the Microsoft On The Issues blog.
Note: This is an active incident. We will post more details here as they become available.
NOBELIUM has historically targeted government organizations, non-government organizations (NGOs), think tanks, military, IT service providers, health technology and research, and telecommunications providers. With this latest attack, NOBELIUM attempted to target approximately 3,000 individual accounts across more than 150 organizations, employing an established pattern of using unique infrastructure and tooling for each target, increasing their ability to remain undetected for a longer period of time.
This new wide-scale email campaign leverages the legitimate service Constant Contact to send malicious links that were obscured behind the mailing service’s URL (many email and document services provide a mechanism to simplify the sharing of files, providing insights into who and when links are clicked). Due to the high volume of emails distributed in this campaign, automated email threat detection systems blocked most of the malicious emails and marked them as spam. However, some automated threat detection systems may have successfully delivered some of the earlier emails to recipients either due to configuration and policy settings or prior to detections being in place.
Due to the fast-moving nature of this campaign and its perceived scope, Microsoft encourages organizations to investigate and monitor communications matching characteristics described in this report and take the actions described below in this article.
We continue to see an increase in sophisticated and nation-state-sponsored attacks and, as part of our ongoing threat research and efforts to protect customers, we will continue to provide guidance to the security community on how to secure against and respond to these multi-dimensional attacks.