Sigma rule: Cross Site Scripting Strings

Rule

Title

Cross Site Scripting Strings

Status

test

Level

high

Author

Saw Win Naung, Nasreddine Bencherchali

Date

2021-08-15

Modified

2022-06-14

File

rules/web/webserver_generic/web_xss_in_access_logs.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects XSS attempts injected via GET requests in access logs

Log source

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

False positives (as the rule lists them)

• 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

Tags

• attack.initial-access
• attack.t1189

MITRE ATT&CK ids this rule names

• T1189

References

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/web/webserver_generic/web_xss_in_access_logs.yml