MediumSplunk security content Michael Haag +1

Detect Empire with PowerShell Script Block Logging

Description

The following analytic detects suspicious PowerShell execution indicative of PowerShell-Empire activity. It leverages PowerShell Script Block Logging (EventCode=4104) to capture and analyze commands sent to PowerShell, specifically looking for patterns involving `system.net.webclient` and base64 encoding. This behavior is significant as it often represents initial stagers used by PowerShell-Empire, a known post-exploitation framework. If confirmed malicious, this activity could allow attackers to download and execute additional payloads, leading to potential code execution, data exfiltration, or further compromise of the affected system.

Detection logic

Detection requirements

Platform: Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source category: powershell_script_block_logging_4104

Known benign triggers

False positives may only pertain to it not being related to Empire, but another framework. Filter as needed if any applications use the same pattern.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
blog.palantir.com/tampering-with-windows-event-tracing-background-offense-and-defense-4be7ac62ac63	Unclassified	19from 2 sources
github.com/BC-SECURITY/Empire	Tool	3from 3 sources
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.	Product documentation	15
static1.squarespace.com/static/552092d5e4b0661088167e5c/t/59c1814829f18782e24f1fe2/1505853768977/Windows+PowerShell+Logging+Cheat+Sheet+ver+Sept+2017+v2.1.pdf	Unclassified	17
www.crowdstrike.com/blog/investigating-powershell-command-and-script-logging/	Security research	17
www.splunk.com/en_us/blog/security/hunting-for-malicious-powershell-using-script-block-logging.html	Security research	14

Detection rules

Detect Empire with PowerShell Script Block Logging

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules