Webserver GET requests containing XSS-related payload strings

Finds likely XSS injection attempts in webserver GET requests by matching script, tag, and JS payload strings while excluding 404s.

FreeReviewedSigma · High · v2

Category: webserver
Author: Saw Win Naung, Nasreddine Bencherchali (SigmaHQ), DRL 1.1
Published: 2021-08-15
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1189Drive-by Compromise
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags webserver access log entries for GET requests that include common XSS injection patterns such as encoded and double-encoded <script>, <iframe>, <svg> payloads and JavaScript event handlers or alert invocations. Attackers often use these crafted strings in query parameters to trigger script execution in other users’ browsers. The detection relies on HTTP method, matched keyword substrings, and excludes events with a 404 status.

Reporting behind it

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Webserver GET requests containing XSS-related payload strings

Pivot detection · T1189 · 6 related

Changelog

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.

webserver-xss-payload-strings-in-get-request-urls-access-logs-65354b83

title: Webserver GET requests containing XSS-related payload strings
id: 95095461-3c9a-413f-a654-1df90c7fad39
status: test
description: This rule flags webserver access log entries for GET requests that include common XSS injection patterns such as encoded and double-encoded <script>, <iframe>, <svg> payloads and JavaScript event handlers or alert invocations. Attackers often use these crafted strings in query parameters to trigger script execution in other users’ browsers. The detection relies on HTTP method, matched keyword substrings, and excludes events with a 404 status.
references:
  - https://github.com/payloadbox/xss-payload-list
  - https://portswigger.net/web-security/cross-site-scripting/contexts
  - https://github.com/SigmaHQ/sigma/blob/master/rules/web/webserver_generic/web_xss_in_access_logs.yml
author: Saw Win Naung, Nasreddine Bencherchali, Huntrule Team
date: 2021-08-15
modified: 2022-06-14
tags:
  - attack.initial-access
  - attack.t1189
logsource:
  category: webserver
detection:
  select_method:
    cs-method: GET
  keywords:
    - =<script>
    - =%3Cscript%3E
    - =%253Cscript%253E
    - "<iframe "
    - "%3Ciframe "
    - "<svg "
    - "%3Csvg "
    - document.cookie
    - document.domain
    - " onerror="
    - " onresize="
    - ' onload="'
    - onmouseover=
    - ${alert
    - javascript:alert
    - javascript%3Aalert
  filter:
    sc-status: 404
  condition: select_method and keywords and not filter
falsepositives:
  - JavaScripts,CSS Files and PNG files
  - User searches in search boxes of the respective website
  - Internal vulnerability scanners can cause some serious FPs when used, if you experience a lot of FPs due to this think of adding more filters such as "User Agent" strings and more response codes
level: high
license: DRL-1.1
related:
  - id: 65354b83-a2ea-4ea6-8414-3ab38be0d409
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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