2.3.11.11 (L1) Ensure 'Network security: Restrict NTLM: Audit Incoming NTLM Traffic' is set to 'Enable auditing for all accounts'

Information

This policy setting allows the auditing of incoming NTLM traffic. Events for this setting are recorded in the operational event log (e.g. Applications and Services Log\Microsoft\Windows\NTLM).

The recommended state for this setting is: Enable auditing for all accounts

Auditing and monitoring NTLM traffic can assist in identifying systems using this outdated authentication protocol, so they can be remediated to using a more secure protocol, such as Kerberos. The log information gathered can also assist in forensic investigations after a malicious attack.

NTLM and NTLMv2 authentication is vulnerable to various attacks, including SMB relay, man-in-the-middle, and brute force attacks. Reducing and eliminating NTLM authentication in an environment reduces the risk of an attacker gaining access to systems on the network.

Solution

To establish the recommended configuration via GP, set the following UI path to Enable auditing for all accounts :

Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options\Network security: Restrict NTLM: Audit Incoming NTLM Traffic

Impact:

The event log will contain information on incoming NTLM authentication traffic.

See Also

https://workbench.cisecurity.org/benchmarks/17603