InformationalSplunk security content Teoderick Contreras +1

Powershell Processing Stream Of Data

Description

The following analytic detects suspicious PowerShell script execution involving compressed stream data processing, identified via EventCode 4104. It leverages PowerShell Script Block Logging to flag scripts using `IO.Compression`, `IO.StreamReader`, or decompression methods. This activity is significant as it often indicates obfuscated PowerShell or embedded .NET/binary execution, which are common tactics for evading detection. If confirmed malicious, this behavior could allow attackers to execute hidden code, escalate privileges, or maintain persistence within the environment.

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

powershell may used this function to process compressed data.

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
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	3
medium.com/@ahmedjouini99/deobfuscating-emotets-powershell-payload-e39fb116f7b9	Unclassified	Only this detection cites it
static1.squarespace.com/static/552092d5e4b0661088167e5c/t/59c1814829f18782e24f1fe2/1505853768977/Windows+PowerShell+Logging+Cheat+Sheet+ver+Sept+2017+v2.1.pdf	Unclassified	17
thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/	Threat report	12
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

Powershell Processing Stream Of Data

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules