An ongoing brute-force attack campaign targeting enterprise cloud environments has been spearheaded by the Russian military intelligence since mid-2019, according to a joint advisory published by intelligence agencies in the U.K. and U.S.

The National Security Agency (NSA), Cybersecurity and Infrastructure Security Agency (CISA), Federal Bureau of Investigation (FBI), and the U.K.'s National Cyber Security Centre (NCSC) formally attributed the incursions to the Russian General Staff Main Intelligence Directorate (GRU) 85th Main Special Service Center (GTsSS).

The threat actor is also tracked under various monikers, including APT28 (FireEye Mandiant), Fancy Bear (CrowdStrike), Sofacy (Kaspersky), STRONTIUM (Microsoft), and Iron Twilight (Secureworks).

APT28 has a track record of using password spray and brute-force login attempts to steal login credentials. In November 2020, Microsoft disclosed cyberattacks staged by the adversary aimed at companies involved in researching vaccines and treatments for COVID-19. What's different this time around is the actor's reliance on software containers to scale its brute-force attempts.

"The campaign uses a Kubernetes cluster in brute force access attempts against the enterprise and cloud environments of government and private sector targets worldwide," CISA said. "After obtaining credentials via brute force, the GTsSS uses a variety of known vulnerabilities for further network access via remote code execution and lateral movement."

Some of the other security flaws exploited by APT28 to pivot inside the breached organizations and gain access to internal email servers include -

• CVE-2020-0688 - Microsoft Exchange Validation Key Remote Code Execution Vulnerability
• CVE-2020-17144 - Microsoft Exchange Remote Code Execution Vulnerability

The threat actors is also said to utilized different evasion techniques in an attempt to disguise some components of their operations, including routing brute-force authentication attempts through Tor and commercial VPN services, including CactusVPN, IPVanish, NordVPN, ProtonVPN, Surfshark, and WorldVPN.

The agencies said the attacks primarily focused on the U.S. and Europe, targeting government and military, defense contractors, energy companies, higher education, logistics companies, law firms, media companies, political consultants or political parties, and think tanks.

"Network managers should adopt and expand usage of multi-factor authentication to help counter the effectiveness of this capability," the advisory noted. "Additional mitigations to ensure strong access controls include time-out and lock-out features, the mandatory use of strong passwords, implementation of a Zero Trust security model that uses additional attributes when determining access, and analytics to detect anomalous accesses."