SolarWinds Orion Web API auth bypass probing via suspicious WebResource requests

Detects likely SolarWinds Orion API authentication bypass probing by matching suspicious WebResource/i18n endpoint query strings while filtering known valid requests.

FreeReviewedSigma · Critical · v5

Category: webserver
Author: Bhabesh Raj, Tim Shelton (SigmaHQ), DRL 1.1
Published: 2020-12-27
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags HTTP requests whose URI query contains specific ASP.NET handler and i18n paths commonly associated with SolarWinds Orion API bypass attempts. Attackers may use crafted Orion endpoints to evade authentication and interact with internal functionality. The detection relies on webserver request telemetry, matching on `cs-uri-query` substrings for the targeted handler paths and the presence of SolarWinds API-related URI segments, while excluding known valid request patterns.

Reporting behind it

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SolarWinds Orion Web API auth bypass probing via suspicious WebResource requests

Pivot detection · T1190 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

solarwinds-orion-api-auth-bypass-probing-via-suspicious-webresource-axd-and-i18n-5a35116f

title: SolarWinds Orion Web API auth bypass probing via suspicious WebResource requests
id: 425b76b2-9e51-401d-be66-2b3477a2e36c
status: test
description: This rule flags HTTP requests whose URI query contains specific ASP.NET handler and i18n paths commonly associated with SolarWinds Orion API bypass attempts. Attackers may use crafted Orion endpoints to evade authentication and interact with internal functionality. The detection relies on webserver request telemetry, matching on `cs-uri-query` substrings for the targeted handler paths and the presence of SolarWinds API-related URI segments, while excluding known valid request patterns.
references:
  - https://kb.cert.org/vuls/id/843464
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/Exploits/CVE-2020-10148/web_cve_2020_10148_solarwinds_exploit.yml
author: Bhabesh Raj, Tim Shelton, Huntrule Team
date: 2020-12-27
modified: 2023-01-02
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2020-10148
  - detection.emerging-threats
logsource:
  category: webserver
detection:
  selection:
    cs-uri-query|contains:
      - /WebResource.axd
      - /ScriptResource.axd
      - /i18n.ashx
      - /Skipi18n
  selection2:
    cs-uri-query|contains:
      - /SolarWinds/
      - /api/
  valid_request_1:
    cs-uri-query|contains: Orion/Skipi18n/Profiler/
  valid_request_2:
    cs-uri-query|contains:
      - css.i18n.ashx
      - js.i18n.ashx
  condition: all of selection* and not 1 of valid_request_*
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: 5a35116f-43bc-4901-b62d-ef131f42a9af
    type: derived

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