Multiple Users Failing To Authenticate From Host Using Ntlm

Multiple Users Failing To Authenticate From Host Using Ntlm


The following analytic identifies one source endpoint failing to authenticate with multiple valid users using the NTLM protocol. This behavior could represent an adversary performing a Password Spraying attack against an Active Directory environment using NTLM to obtain initial access or elevate privileges. Event 4776 is generated on the computer that is authoritative for the provided credentials. For domain accounts, the domain controller is authoritative. For local accounts, the local computer is authoritative. Error code 0xC000006A means: misspelled or bad password (the attempted user is a legitimate domain user).\ The detection calculates the standard deviation for each host and leverages the 3-sigma statistical rule to identify an unusual number of users. To customize this analytic, users can try different combinations of the bucket span time and the calculation of the upperBound field. This logic can be used for real time security monitoring as well as threat hunting exercises.\ This detection will only trigger on domain controllers, not on member servers or workstations.\ The analytics returned fields allow analysts to investigate the event further by providing fields like source workstation name and attempted user accounts.


Multiple Users Failing To Authenticate From Host Using Ntlm Help

To successfully implement this search, you need to be ingesting Domain Controller events. The Advanced Security Audit policy setting Audit Credential Validation within Account Logon needs to be enabled.


Open in Search