PH_RULE_O365_BruteForceAttemptSameSource
Enabled
Office365 has reported more than 5 login failure attempts from the same source IP in a 15 minute period.
7
Security
Credential Access
Credential Access consists of techniques for stealing credentials like account names and passwords. Techniques used to get credentials include keylogging or credential dumping. Using legitimate credentials can give adversaries access to systems, make them harder to detect, and provide the opportunity to create more accounts to help achieve their goals.
https://attack.mitre.org/tactics/TA0006T1110.003
Brute Force: Password Spraying
Adversaries may use a single or small list of commonly used passwords against many different accounts to attempt to acquire valid account credentials.
https://attack.mitre.org/techniques/T1110/003Application
Office 365 via Management Activity API
Correlation
Identify the source of the incident and the user and make sure that it is a legitimate attempt to log on to the system. Make sure it is not a cached credential from another system while the primary user has changed credential. Make sure there are no other incidents from the source host that may indicate malware trying to gain access to other systems. Make sure there are no vulnerabilities on the source and destination hosts.
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
900 seconds
If the following defined pattern/s occur within a 900 second time window.
brute_force
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType IN ("MS_OFFICE365_EntraID_UserLoginFailed","MS_OFFICE365_EntraID_StsLogon_UserLoginFailed")
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
srcIpAddr
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 5
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
srcIpAddr=brute_force.srcIpAddr