Cross Site Scripting Strings — Sigma Rule

Rule metadata and linked tags

Author: Saw Win Naung, Nasreddine Bencherchali. Source status: test; severity: high. Source dates: 2021-08-15 / 2022-06-14.

{
  "category": "webserver"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: aecf13dfffc0d341a27fa2bb93f15c54512c7ee78107195526ff3f2bece27144

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Cross Site Scripting Strings
id: 65354b83-a2ea-4ea6-8414-3ab38be0d409
status: test
description: Detects XSS attempts injected via GET requests in access logs
references:
    - https://github.com/payloadbox/xss-payload-list
    - https://portswigger.net/web-security/cross-site-scripting/contexts
author: Saw Win Naung, Nasreddine Bencherchali
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

Original YAML and metadata in JSON

False positives

• 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

Source references

• https://github.com/payloadbox/xss-payload-list
• https://portswigger.net/web-security/cross-site-scripting/contexts