The Microsoft Threat Intelligence Center (MSTIC) has released a blog post describing an increase in malicious cyber activity from the Iranian group known as Phosphorus. These threat actors are exploiting password reset or account recovery features to take control of targeted email accounts.
In a 30-day period between August and September, the Microsoft Threat Intelligence Center (MSTIC) observed Phosphorus making more than 2,700 attempts to identify consumer email accounts belonging to specific Microsoft customers and then attack 241 of those accounts.
The targeted accounts are associated with a U.S. presidential campaign, current and former U.S. government officials, journalists covering global politics and prominent Iranians living outside Iran. Four accounts were compromised as a result of these attempts; these four accounts were not associated with the U.S. presidential campaign or current and former U.S. government officials.
Microsoft has notified the customers related to these investigations and threats and has worked as requested with those whose accounts were compromised to secure them.
Phosphorus used information gathered from researching their targets or other means to game password reset or account recovery features and attempt to take over some targeted accounts. For example, they would seek access to a secondary email account linked to a user’s Microsoft account, then attempt to gain access to a user’s Microsoft account through verification sent to the secondary account.
In some instances, they gathered phone numbers belonging to their targets and used them to assist in authenticating password resets.
People can also periodically check their login history, and we recommend this for journalists, political campaigns staff, and others interested in assuring account security. These logs are made available through the Account Security Sign-In Activity tab.