Detect Copy of ShadowCopy with Script Block Logging
Description
The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify suspicious PowerShell execution. Script Block Logging captures the command sent to PowerShell, the full command to be executed. Upon enabling, logs will output to Windows event logs. Dependent upon volume, enable on critical endpoints or all.
This analytic identifies copy
or [System.IO.File]::Copy
being used to capture the SAM, SYSTEM or SECURITY hives identified in script block. This will catch the most basic use cases for credentials being taken for offline cracking.
During triage, review parallel processes using an EDR product or 4688 events. It will be important to understand the timeline of events around this activity. Review the entire logged PowerShell script block.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2021-07-21
- Author: Michael Haag, Splunk
- ID: 9251299c-ea5b-11eb-a8de-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
ID | Summary | CVSS |
---|---|---|
CVE-2021-36934 | Windows Elevation of Privilege Vulnerability | 4.6 |
Search
1
2
3
4
5
`powershell` EventCode=4104 Message IN ("*copy*","*[System.IO.File]::Copy*") AND Message IN ("*System32\\config\\SAM*", "*System32\\config\\SYSTEM*","*System32\\config\\SECURITY*")
| stats count min(_time) as firstTime max(_time) as lastTime by OpCode ComputerName User EventCode Message
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `detect_copy_of_shadowcopy_with_script_block_logging_filter`
Macros
The SPL above uses the following Macros:
detect_copy_of_shadowcopy_with_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
- Message
- OpCode
- ComputerName
- User
- 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
Limited false positives as the scope is limited to SAM, SYSTEM and SECURITY hives.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
80.0 | 80 | 100 | PowerShell was identified running a script to capture the SAM hive on endpoint $ComputerName$ by user $User$. |
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
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934
- https://github.com/GossiTheDog/HiveNightmare
- https://github.com/JumpsecLabs/Guidance-Advice/tree/main/SAM_Permissions
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
source | version: 1