Splunk unknown experimental spl

Supernova Webshell

The following analytic detects the presence of the Supernova webshell, used in the SUNBURST attack, by identifying specific patterns in web URLs. The detection leverages Splunk to search for URLs containing "*logoimagehandler.ashx*codes*", "*logoimagehandler.ashx*clazz*", "*logoimagehandler.ashx*method*", and "*logoimagehandler.ashx*args*". This activity is significant as it indicates potential unauthorized access and arbitrary code execution on a compromised system. If confirmed malicious, this could lead to data theft, ransomware deployment, or other severe outcomes. Immediate steps include reviewing the web URLs, inspecting on-disk artifacts, and analyzing concurrent processes and network connections.

View Source

Detection Logic

| tstats `security_content_summariesonly` count 
FROM datamodel=Web.Web
  
WHERE web.url=*logoimagehandler.ashx*codes*
    
OR
    Web.url=*logoimagehandler.ashx*clazz*
    
OR
    Web.url=*logoimagehandler.ashx*method*
    
OR
    Web.url=*logoimagehandler.ashx*args*
  BY Web.src Web.dest Web.url
     Web.vendor_product Web.user Web.http_user_agent
     _time span=1s
| `supernova_webshell_filter`

False Positives

⚠ There might be false positives associted with this detection since items like args as a web argument is pretty generic.

Field Validations

Loading…

Comments (0)

Loading comments...