splApache-2.0from splunk/security_content

Detect Password Spray Attack Behavior From Source

The following analytic identifies one source failing to authenticate with 10 or more unique users. This behavior could represent an adversary performing a Password Spraying attack to obtain initial access or elevate privileges. This logic can be used for real time security monitoring as well as threat hunting exercises and works well against any number of data sources ingested into the CIM datamodel. Environments can be very different depending on the organization. Test and customize this detections thresholds if needed.

Quality

FP risk

—

Forks

Views

Rule sourcedetections/endpoint/detect_password_spray_attack_behavior_from_source.yml

| tstats `security_content_summariesonly` max(_time) as lastTime, min(_time) as firstTime, values(Authentication.user_category) as user_category values(Authentication.src_category) as src_category values(Authentication.app) as app count FROM datamodel=Authentication.Authentication
  BY Authentication.action Authentication.app Authentication.authentication_method
     Authentication.dest Authentication.signature Authentication.signature_id
     Authentication.src Authentication.user
| `drop_dm_object_name("Authentication")`
| eval user=case((match(upper(user),"[a-zA-Z0-9]{3}")),upper(user),true(),null), src=upper(src), success=if(action="success",count,0),success_user=if(action="success",user,null),failure=if(action="failure",count,0), failed_user=if(action="failure",user,null)
| stats count min(firstTime) as firstTime max(lastTime) as lastTime values(app) as app values(src_category) as src_category values(success_user) as user values(failed_user) as failed_user dc(success_user) as success_dc dc(failed_user) as failed_dc dc(user) as user_dc ,sum(failure) as failure,sum(success) as success
  BY src
| fields - _time
| where user_dc >= 10 AND .25 > (success/failure) AND failed_dc > success_dc
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `detect_password_spray_attack_behavior_from_source_filter`