CVE-2017-1002201 in haml
Summary
by MITRE
In haml versions prior to version 5.0.0.beta.2, when using user input to perform tasks on the server, characters like < > " ' must be escaped properly. In this case, the ' character was missed. An attacker can manipulate the input to introduce additional attributes, potentially executing code.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability identified as CVE-2017-1002201 affects the haml templating engine, a widely used Ruby-based template language that simplifies HTML generation. This issue exists in versions prior to 5.0.0.beta.2 and represents a critical security flaw that stems from inadequate input sanitization. The vulnerability specifically manifests when user-provided data is processed within haml templates, creating opportunities for malicious actors to exploit improper escaping mechanisms. The core problem lies in the insufficient handling of single quotation marks within the templating engine's escape routines, which creates a pathway for code injection attacks.
This vulnerability maps directly to CWE-79, which describes Cross-Site Scripting (XSS) conditions, and CWE-94, which covers External Control of System or Configuration Setting. The technical flaw occurs because haml fails to properly escape the apostrophe character when processing user input, allowing attackers to inject additional attributes into HTML elements. When user data containing unescaped single quotes is rendered within templates, it can be manipulated to introduce malformed HTML attributes that bypass security checks. The vulnerability specifically impacts how the templating engine handles attribute values, particularly in scenarios where dynamic content is inserted into HTML attributes without proper sanitization.
The operational impact of this vulnerability is severe as it enables remote code execution through carefully crafted input sequences. Attackers can leverage this weakness to inject malicious attributes into HTML elements, potentially leading to arbitrary code execution on the server or client-side attacks. The vulnerability's exploitation requires minimal privileges and can be executed through standard user input mechanisms such as form submissions, API endpoints, or any interface that processes user-provided data within haml templates. This creates a significant risk for web applications that rely on haml for rendering dynamic content, particularly those handling untrusted user input.
Mitigation strategies for CVE-2017-1002201 should prioritize immediate version upgrades to haml 5.0.0.beta.2 or later, which contain the necessary escaping fixes. Organizations should also implement comprehensive input validation and sanitization measures, ensuring all user-provided data is properly escaped before template processing. The implementation of Content Security Policy headers and regular security audits can provide additional defense layers. Additionally, developers should follow secure coding practices as outlined in the OWASP Secure Coding Practices, particularly focusing on proper output encoding in templating contexts. The vulnerability highlights the importance of adhering to the principle of least privilege and implementing proper input validation at all levels of application processing, aligning with ATT&CK technique T1068 which covers Exploitation for Privilege Escalation through improper input handling and validation.