In Splunk Enterprise versions below 9.4.3, 9.3.5, 9.2.7 and 9.1.10, and Splunk Cloud Platform versions below 9.3.2411.104, 9.3.2408.114, and 9.2.2406.119, an unauthenticated attacker can send a specially-crafted SPL search that could change the membership state in a Splunk Search Head Cluster (SHC) through a Cross-Site Request Forgery (CSRF), potentially leading to the removal of the captain or a member of the SHC.The vulnerability requires the attacker to phish the administrator-level victim by tricking them into initiating a request within their browser. The attacker should not be able to exploit the vulnerability at will.
Weakness
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.
Potential Mitigations
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]
- Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
- Use the “double-submitted cookie” method as described by Felten and Zeller:
- When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user’s machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.
- Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.
- This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]
References