Since early March 2025, suspected Russia-linked hackers have been targeting individuals and organizations tied to Ukraine and human rights. These actors have shifted tactics, moving away from device code phishing to a more personalized approach that involves direct interaction with targets. Their goal is to access Microsoft 365 accounts through social engineering techniques that exploit legitimate Microsoft OAuth 2.0 workflows. Volexity researchers tracked at least two threat clusters, UTA0352 and UTA0355, behind the campaigns, noting potential ties to other groups like APT29.
The attacks involve impersonating European officials and using compromised Ukrainian government accounts to trick targets into sharing Microsoft-generated OAuth codes. Victims are contacted through messaging platforms like Signal and WhatsApp, with the attackers arranging private meetings and sending links to the official Microsoft 365 login page. The links direct victims to authenticate through Microsoft’s infrastructure, which then generates an OAuth token for attackers. This method allows the attackers to gain access to the victim’s Microsoft 365 account without needing additional user interaction.
The attack continues by redirecting victims to a Visual Studio Code page or a blank redirect, where the attacker requests the OAuth code directly from the victim. This OAuth code enables the attackers to generate access tokens that grant unauthorized access to the target’s account. The attackers also used compromised Ukrainian email accounts to send phishing emails and follow up with messages on Signal or WhatsApp to deepen the deception. These attacks are sophisticated in nature, utilizing social engineering alongside Microsoft’s trusted infrastructure.
Security experts advise organizations to closely monitor newly registered devices and educate employees on the risks of unsolicited contact via messaging apps. It’s crucial for organizations to implement conditional access policies and audit access attempts from unapproved devices. As these attacks exploit Microsoft’s legitimate authentication infrastructure, they remain difficult to detect, highlighting the need for proactive defense strategies and vigilance against social engineering tactics.
