A recent vulnerability, designated CVE-2022-45397, has been discovered in the Jenkins OSF Builder Suite - XML Linter Plugin 1..2, and earlier versions. This vulnerability exposes the plugin to XML External Entity (XXE) attacks, which can expose sensitive information and lead to a variety of other security risks. This post will provide an overview of the vulnerability, an example of an exploitable code snippet, links to original references, and details on the potential exploits associated with this vulnerability.

What is an XXE Attack?
An XML External Entity (XXE) attack occurs when an adversary exploits an improperly configured XML parser to access or interact with external entities, potentially exposing sensitive information or leading to denial of service. To read more on this type of attack, check out the OWASP's XXE cheat sheet (https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html).

Code snippet showcasing the vulnerability

The XXE vulnerability in the Jenkins OSF Builder Suite - XML Linter Plugin 1..2 and earlier results from the plugin not configuring its XML parser to prevent XXE attacks. The following is an example of a vulnerable code snippet:

public void parseDocument(byte[] document) {
    try {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        InputSource is = new InputSource(new ByteArrayInputStream(document));
        Document doc = builder.parse(is);
        // Rest of the processing
    } catch (ParserConfigurationException | SAXException | IOException e) {
        // Handle exception
    }
}

In this code snippet, the XML parser is not appropriately configured to prevent XXE attacks. Hence, the plugin is vulnerable to such attacks.

1. Jenkins Security Advisory: https://www.jenkins.io/security/advisory/2022-02-22/
2. CVE Details: https://nvd.nist.gov/vuln/detail/CVE-2022-45397
3. XML Linter Plugin Repository: https://github.com/jenkinsci/osf-builder-suite-xml-linter-plugin

Exploit Details

An attacker might use an XXE attack on a vulnerable plugin for one or multiple malicious objectives, such as:

Accessing sensitive system files or data stored on the server hosting the Jenkins instance.

2. Performing Server Side Request Forgery (SSRF) attacks by sending arbitrary HTTP requests to other internal systems in the network.

Mitigation

Users of the affected Jenkins OSF Builder Suite - XML Linter Plugin 1..2 and earlier should update to the latest version with the appropriate security fix. Additionally, ensure that the XML parser used in the plugin is configured to prevent XXE attacks by following the recommendations of the OWASP XXE prevention cheat sheet (https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html).

In conclusion, CVE-2022-45397 highlights the importance of proper configuration and security measures for XML parsers and Jenkins plugins to prevent potential XXE attacks. Updating the affected plugin to the latest version and ensuring that the XML parser is properly configured will help protect against such attacks and maintain a secure Jenkins environment.

Timeline

Published on: 11/15/2022 20:15:00 UTC
Last modified on: 11/20/2022 03:08:00 UTC