Add vpatch-CVE-2021-25281 rule and test

[crowdsec-automation]

This rule detects exploitation attempts for CVE-2021-25281, an authentication bypass in SaltStack Salt's API. The vulnerability is triggered when an unauthenticated attacker sends a POST request to the /run endpoint with a JSON body where the client parameter is set to wheel_async. This allows attackers to execute arbitrary wheel modules without proper authentication.

• The first rule condition matches requests to the /run endpoint, using a case-insensitive comparison (lowercase transform and equals match).
• The second rule condition inspects the JSON body for the client parameter (using the json.client variable in the BODY_ARGS zone) and checks if its value is exactly wheel_async, again with a lowercase transform for normalization.
• This approach ensures that only requests specifically targeting the vulnerable functionality are detected, minimizing false positives.
• The labels section includes the correct CVE, ATT&CK, and CWE references, and the product/vuln class label is formatted as required.

Validation checklist:

• All value: fields are lowercase.
• All relevant transforms include lowercase.
• No match.value contains capital letters.
• The rule uses equals for exact matches and contains where appropriate (not needed here).
• No use of both and and or in the same rule.

[github-actions]

Hello @crowdsec-automation and thank you for your contribution!

❗ It seems that the following scenarios are not part of the 'crowdsecurity/appsec-virtual-patching' collection:

🔴 crowdsecurity/vpatch-CVE-2021-25281 🔴

[github-actions]

Hello @crowdsec-automation and thank you for your contribution!

I'm a bot that helps maintainers to validate scenarios and ensure they include all the required information.
I've found some errors in your scenarios, please fix them and re-submit your PR, or ask for help if you need it.

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crowdsecurity/crs-exclusion-plugin-cpanel:

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crowdsecurity/crs-exclusion-plugin-drupal:

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crowdsecurity/crs-exclusion-plugin-phpmyadmin:

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crowdsecurity/crs-exclusion-plugin-xenforo:

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Mitre ATT&CK

Information about mitre attack can be found here.
As an example, some common mitre attack techniques:

• T1110 for bruteforce attacks
• T1595 and T1190 for exploitation of public vulnerabilities
• T1595 for generic scanning of exposed applications

Expected format is (where XXXX is the technique ID):

labels:
  classification:
    - attack.TXXXX

CVEs

If your scenario covers a specific CVE (Common Vulnerabilities and Exposures), please add it.

Expected format is (where CVE-XXX-XXX is the CVE ID):

labels:
  classification:
    - cve.CVE-XXX-XXX

Behaviors

Please identify the behavior(s) your scenario is targeting. You can find the list of available behaviors here.

Expected format is (where <behavior> is the behavior you want to target):

labels:
  behavior: <behavior>

See the labels documentation for more information.