CVE-2015-3161 in Beaker
Summary
by MITRE
The search bar code in bkr/server/widgets.py in Beaker before 20.1 does not escape </script> tags in string literals when producing JSON.
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Analysis
by VulDB Data Team • 12/30/2019
The vulnerability identified as CVE-2015-3161 resides within the Beaker continuous integration and testing platform, specifically in the server widgets component that handles search functionality. This issue affects versions prior to 20.1 and represents a critical security flaw that could enable malicious actors to inject arbitrary JavaScript code into the application's output. The vulnerability manifests in the bkr/server/widgets.py file where the search bar implementation fails to properly sanitize user input before incorporating it into JSON responses. This particular flaw falls under the category of cross-site scripting attacks, specifically representing a variant of reflected XSS where the malicious payload is embedded within the search query itself.
The technical implementation of this vulnerability stems from improper input sanitization within the JSON generation process. When users submit search queries containing special characters, particularly the sequence </script>, the application fails to escape these characters before including them in the JSON response. This oversight creates a condition where an attacker can inject JavaScript code that will execute in the context of other users' browsers when they view the search results. The vulnerability directly relates to CWE-79 which defines improper neutralization of input during web page generation, specifically covering cross-site scripting scenarios. The flaw represents a classic example of insufficient output escaping where the application assumes that user input will not contain malicious content that could alter the structure of the generated JSON and subsequently execute in browser contexts.
The operational impact of this vulnerability extends beyond simple data theft or session hijacking, as it enables attackers to potentially gain full control over user sessions and execute arbitrary commands on behalf of authenticated users. When combined with other attack vectors, this vulnerability could allow adversaries to escalate privileges, access sensitive data, or perform unauthorized actions within the Beaker platform. The attack surface is particularly concerning given that search functionality is typically accessible to all users, including unauthenticated ones, making this vulnerability exploitable by anyone with access to the system. This weakness aligns with ATT&CK technique T1213 which covers data from information repositories and can be leveraged to establish persistent access or conduct more sophisticated attacks once initial compromise is achieved.
Mitigation strategies for this vulnerability involve implementing proper input sanitization and output escaping mechanisms throughout the application's data flow. The primary fix requires modifying the search bar implementation to escape special characters including the closing script tag sequence before incorporating user input into JSON responses. Organizations should implement a comprehensive input validation framework that properly encodes all user-supplied data before inclusion in any dynamic content. Additionally, the application should employ Content Security Policy headers to prevent unauthorized script execution, though this serves as a secondary defense mechanism rather than a primary fix. The recommended approach includes adopting a whitelist-based input validation strategy where only known safe characters are accepted, combined with proper HTML escaping for any data that must be rendered in browser contexts. Regular security audits and code reviews should specifically target data handling routines to prevent similar issues from emerging in other parts of the application.