Detect Certify With PowerShell Script Block Logging
Description
The following analytic detects the use of the Certify tool via an in-memory PowerShell function to enumerate Active Directory Certificate Services (AD CS) environments. It leverages PowerShell Script Block Logging (EventCode 4104) to identify specific command patterns associated with Certify's enumeration and exploitation functions. This activity is significant as it indicates potential reconnaissance or exploitation attempts against AD CS, which could lead to unauthorized certificate issuance. If confirmed malicious, attackers could leverage this to escalate privileges, persist in the environment, or access sensitive information by abusing AD CS.
Query · spl
`powershell` EventCode=4104 (ScriptBlockText IN ("*find *") AND ScriptBlockText IN ("* /vulnerable*","* -vulnerable*","* /enrolleeSuppliesSubject *","* /json /outfile*")) OR (ScriptBlockText IN (,"*auth *","*req *",) AND ScriptBlockText IN ("* -ca *","* -username *","* -u *")) OR (ScriptBlockText IN ("*request *","*download *") AND ScriptBlockText IN ("* /ca:*"))
| fillnull
| stats count min(_time) as firstTime max(_time) as lastTime
BY dest signature signature_id
user_id vendor_product EventID
Guid Opcode Name
Path ProcessID ScriptBlockId
ScriptBlockText
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| eval file_name = case(isnotnull(file_name),file_name,true(),"unknown")
| eval signature = substr(command,0,256)
| `detect_certify_with_powershell_script_block_logging_filter`
Implementation guide
To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba..
Known false positives
- No false positives have been identified at this time.
Analyst notes
Known false positives: No false positives have been identified at this time.