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?)
OS-WINDOWS Microsoft Windows NetrServerReqChallenge RPC transport sign and seal disabling attempt
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.
No public information
No known false positives
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:
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
CVE-2020-1472An elevation of privilege vulnerability exists when an attacker establishes a vulnerable Netlogon secure channel connection to a domain controller, using the Netlogon Remote Protocol (MS-NRPC), aka 'Netlogon Elevation of Privilege Vulnerability'.
||Ease of Access||LOW