by microsoft.com — Microsoft successfully detected and disabled attack activity abusing OneDrive by a previously undocumented Lebanon-based activity group Microsoft Threat Intelligence Center (MSTIC) tracks as POLONIUM. The associated indicators and tactics were used by the OneDrive team to improve detection of attack activity and disable offending actor accounts. To further address this abuse, Microsoft has suspended more than 20 malicious OneDrive applications created by POLONIUM actors, notified affected organizations, and deployed a series of security intelligence updates that will quarantine tools developed by POLONIUM operators. Our goal with this blog is to help deter future activity by exposing and sharing the POLONIUM tactics with the community at large.

MSTIC assesses with high confidence that POLONIUM represents an operational group based in Lebanon. We also assess with moderate confidence that the observed activity was coordinated with other actors affiliated with Iran’s Ministry of Intelligence and Security (MOIS), based primarily on victim overlap and commonality of tools and techniques. Such collaboration or direction from Tehran would align with a string of revelations since late 2020 that the Government of Iran is using third parties to carry out cyber operations on their behalf, likely to enhance Iran’s plausible deniability.

POLONIUM has targeted or compromised more than 20 organizations based in Israel and one intergovernmental organization with operations in Lebanon over the past three months. This actor has deployed unique tools that abuse legitimate cloud services for command and control (C2) across most of their victims. POLONIUM was observed creating and using legitimate OneDrive accounts, then utilizing those accounts as C2 to execute part of their attack operation. This activity does not represent any security issues or vulnerabilities on the OneDrive platform. In addition, MSTIC does not, at present, see any links between this activity and other publicly documented groups linked to Lebanon like Volatile Cedar. This blog will also expose further details that show Iranian threat actors may be collaborating with proxies to operationalize their attacks. Microsoft continues to work across its platforms to identify abuse, take down malicious activity, and implement new proactive protections to discourage malicious actors from using our services.

As with any observed nation-state actor activity, Microsoft directly notifies customers that have been targeted or compromised, providing them with the information they need to secure their accounts.