supernova_webshell.yml

name: Supernova Webshell
id: 2ec08a09-9ff1-4dac-b59f-1efd57972ec1
version: 5
date: '2025-04-16'
author: John Stoner, Splunk
status: experimental
type: TTP
description: 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.
data_source: []
search: '| 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`'
how_to_implement: To successfully implement this search, you need to be monitoring
  web traffic to your Solarwinds Orion. The logs should be ingested into splunk and
  populating/mapped to the Web data model.
known_false_positives: There might be false positives associted with this detection
  since items like args as a web argument is pretty generic.
references:
- https://www.splunk.com/en_us/blog/security/detecting-supernova-malware-solarwinds-continued.html
- https://www.guidepointsecurity.com/blog/supernova-solarwinds-net-webshell-analysis/
rba:
  message: Potential Supernova Webshell on $dest$
  risk_objects:
  - field: user
    type: user
    score: 25
  - field: dest
    type: system
    score: 25
  threat_objects: []
tags:
  analytic_story:
  - NOBELIUM Group
  - Earth Alux
  asset_type: Web Server
  mitre_attack_id:
  - T1505.003
  - T1133
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  security_domain: network