Microsoft Says Iranian Hackers Exploiting Zerologon Vulnerability

The Iran-linked threat actor known as MuddyWater is actively targeting the Zerologon vulnerability in Windows Server, Microsoft warns.

Also known as Seedworm, MERCURY, and Static Kitten, and initially analyzed in 2017, MuddyWater is mainly focused on organizations in the Middle East and regions nearby. Highly active, the group was observed expanding its target list and leveraging a broad and varied toolset.

Although further details on the threat actor’s operations emerged last year (after an unknown entity published documents on multiple Iranian groups), and despite security researchers’ scrutiny, MuddyWater continues to evolve its strategies.

According to Microsoft, one of the latest changes in the group’s tactics is the adoption of exploits for Zerologon, a Netlogon remote protocol (MS-NRPC) vulnerability that was addressed in August 2020.

By exploiting the bug, an unauthenticated attacker could gain domain administrator access, resulting in full takeover.

“MSTIC has observed activity by the nation-state actor MERCURY using the CVE-2020-1472 exploit (ZeroLogon) in active campaigns over the last 2 weeks. We strongly recommend patching,” Microsoft said on Twitter.

Both Microsoft and CISA previously issued alerts on attackers targeting the vulnerability, urging administrators to apply the available patches as soon as possible, to all domain controllers in their environments.

In fact, CISA even issued an Emergency Directive requiring all federal agencies to apply the patches immediately. Samba too released fixes for the bug.

The patching of this vulnerability will be done in two stages, Microsoft has revealed. The initial one involves applying the August 2020 fixes, while the second one is an enforcement phase that will start on February 9, 2021.

Last week, Microsoft also announced that the exploitation of Zerologon is now being detected by Microsoft Defender for Identity (previously Azure Advanced Threat Protection) and Microsoft 365 Defender (previously Microsoft Threat Protection).

Related: Microsoft Publishes Guide to Securing Systems Vulnerable to Zerologon Attacks

Related: U.S. Imposes Sanctions on ‘APT39’ Iranian Hackers

Related: CISA Shares Details on Web Shells Employed by Iranian Hackers

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Ionut Arghire is an international correspondent for SecurityWeek.

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