Rule Category

OS-WINDOWS -- Snort has detected traffic targeting vulnerabilities in a Windows-based operating system. This does not include browser traffic or other software on the OS, but attacks against the OS itself. (such as?)

Alert Message

OS-WINDOWS Microsoft Windows NetrServerReqChallenge RPC transport sign and seal disabling attempt

Rule Explanation

This rule looks for a crafted NetrServerReqChallenge dcerpc request where the NegotiationFlags are set in such a way that will disable Secure NRPC's "signing and sealing" or use of Netlogon's secure channel. Microsoft has released updates that allows system administrators to enforce use of secure channels, and notes that "starting with the February 9, 2021 updates where enforcement mode will be enabled on all Windows Domain Controllers, regardless of the registry setting".

What To Look For

This rule looks for an attempt to exploit CVE-2020-1472, an elevation of privilege vulnerability in Netlogon authentication handling.

Known Usage

No public information

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

MITRE ATT&CK Framework

Tactic: Privilege Escalation

Technique: Exploitation for Privilege Escalation

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

Additional Links

Rule Vulnerability

Escalation of Privilege

An Escalation of Privilege (EOP) attack is any attack method that results in a user or application gaining permissions to access resources they normally would not have access to.

CVE Additional Information