Security advisories | Sep 23, 2020

CVE-2020-1472 Zerologon Update

THE THREAT

UPDATE: As of the evening of September 23rd, Microsoft has confirmed that threat actors are exploiting CVE-2020-1472 in attacks in the wild.

The risks posed by CVE-2020-1472 (Zerologon) continues to increase as new Proof-of-Concept (PoC) exploit code has been released. Organizations that have not yet applied the August security updates from Microsoft need to do so as soon as possible to avoid being impacted. On September 18th, eSentire deployed detection for Zerologon to all esLOG customers.

This vulnerability, also known as Zerologon, is a Netlogon elevation of privilege vulnerability, affecting multiple versions of Windows Server [1]. If exploited, threat actors can execute remote code, disable security features, and change computer passwords in Active Directory (AD). eSentire has identified an increase in Proof-of-Concept (PoC) exploit code being publicly released. Exploitation in the wild has not been publicly identified at this time but is expected in the immediate future.

What we’re doing about it

  • esLOG detects exploitation of CVE-2020-1472 (Zerologon)
  • MVS has local plugins to identify this vulnerability
    • MVS customers seeking assistance with their review or scans, please contact your MVS consultant or the eSentire Security Operations Center (SOC)
  • eSentire security teams continue to track this topic for additional details and detection opportunities

What you should do about it

  • After performing a business impact review, apply the official security updates provided by Microsoft
    • If all patches from the August 11th, 2020 Patch Tuesday release have already been applied, no further actions are required

Additional information

As the severity of this vulnerability is Critical and Proof-of-Concept exploit code is widely available, eSentire has published this second advisory to remind clients to mitigate the vulnerability prior to its use in widespread attacks.

Due to the availability of exploit code and the high impact of successful exploitation, real world attacks are expected in the immediate future. Successful exploitation could lead to elevated privileges (such as domain administrator), making this exploit highly valuable for adversaries with a foothold inside of networks. For additional information on this vulnerability, see eSentire’s previous advisory on the release of Proof-of-Concept (PoC) code and technical details for CVE-2020-1472.

Recent Developments:

CISA Emergency Directive

On Friday September 18th, the Cybersecurity and Infrastructure Security Agency (CISA) issued an Emergency Directive to all US federal agencies relating to the Zerologon vulnerability [2]. Federal agencies were given four days to ensure that all vulnerable domain controllers were fully patched. Emergency Directives are an unusual step for government patch management. The directive was issued as there is a high probability that unpatched organizations will be impacted in the immediate future.

Availability and Efficacy of Exploits

The Threat Intelligence team has observed multiple Proof-of-Concept code releases since September 14th, 2020. The availability of exploit code greatly reduces the cost/complexity of weaponizing this vulnerability. Researchers have made improvements on exploit code, such as removing the requirement to reset passwords during exploitation [3]. Benjamin Delpy, author of the Mimikatz suggested adding an exploit for Zerologon in an update to his popular offensive security tool.

References:

[1] https://www.secura.com/pathtoimg.php?id=2055

[2] https://cyber.dhs.gov/ed/20-04/

[3] https://twitter.com/_dirkjan/status/1307662409436475392