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Description

The following analytic identifies when the attacker tool Certify is used through an in-memory PowerShell function to enumerate Active Directory Certificate Services (AD CS) environments. The default command line arguments for the binary version of this tools are similar to PowerShell calls and perform near identical enumeration or exploitation functions.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-06-25
  • Author: Steven Dick
  • ID: f533ca6c-9440-4686-80cb-7f294c07812a

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1649 Steal or Forge Authentication Certificates Credential Access
T1059 Command and Scripting Interpreter Execution
T1059.001 PowerShell Execution
Kill Chain Phase
  • Exploitation
  • Installation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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`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:*")) 
| stats count min(_time) as firstTime max(_time) as lastTime list(ScriptBlockText) as command Values(OpCode) as reason values(Path) as file_name values(UserID) as user by _time Computer EventCode 
| `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) 
| rename Computer as dest,EventCode as signature_id 
| `detect_certify_with_powershell_script_block_logging_filter`

Macros

The SPL above uses the following Macros:

:information_source: detect_certify_with_powershell_script_block_logging_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • ScriptBlockText
  • OpCode
  • Path
  • user
  • Computer
  • EventCode

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell..

Known False Positives

Unknown, partial script block matches.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
90.0 100 90 Certify arguments through PowerShell detected on $dest$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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