CVE-2012-5837 in Firefox
Summary
by MITRE
The Web Developer Toolbar in Mozilla Firefox before 17.0 executes script with chrome privileges, which allows user-assisted remote attackers to conduct cross-site scripting (XSS) attacks via a crafted string.
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Analysis
by VulDB Data Team • 04/19/2021
The vulnerability identified as CVE-2012-5837 resides within the Web Developer Toolbar extension for Mozilla Firefox, a widely used browser tool that provides developers with various debugging and inspection capabilities. This particular flaw represents a critical privilege escalation issue that fundamentally undermines the security boundaries established by Firefox's security model. The vulnerability affects Firefox versions prior to 17.0, where the Web Developer Toolbar extension fails to properly validate or sanitize user input, creating an exploitable condition that can be leveraged by remote attackers.
The technical flaw manifests through the extension's improper handling of script execution within the chrome privilege context. Chrome privileges in Firefox represent the highest level of security clearance within the browser's architecture, allowing extensions to access sensitive browser functionality and potentially manipulate core browser components. When a user visits a malicious website that contains crafted script content, the Web Developer Toolbar extension inadvertently executes this script with elevated privileges instead of the expected user context. This occurs because the extension fails to properly implement security checks that would normally prevent untrusted content from executing with chrome-level permissions.
The operational impact of this vulnerability is severe and directly enables cross-site scripting attacks that can bypass standard browser security mechanisms. Attackers can craft malicious strings that, when processed by the vulnerable Web Developer Toolbar, execute with full chrome privileges, potentially allowing them to access or manipulate browser internals, steal session cookies, read sensitive files, or even inject additional malicious code. The user-assisted nature of this attack means that victims must visit a malicious website and interact with the toolbar extension, but the attack vector remains particularly dangerous as it leverages a legitimate browser tool that users might regularly employ for development work.
This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and demonstrates how extension security can compromise entire browser ecosystems. From an ATT&CK perspective, this represents a privilege escalation technique that can be categorized under T1068, which covers local privilege escalation, and T1566, which covers credential access through social engineering. The attack chain typically involves initial compromise through a malicious website, followed by exploitation of the toolbar extension to gain elevated privileges within the browser environment. The vulnerability also highlights the importance of proper input validation and privilege separation in browser extensions, as outlined in security best practices for web application development.
Mitigation strategies for CVE-2012-5837 primarily focus on updating to Firefox version 17.0 or later, where the Web Developer Toolbar extension was patched to properly handle script execution with appropriate privilege boundaries. Organizations should implement comprehensive browser security policies that include regular updates, extension management, and monitoring for suspicious activity. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping browser extensions updated. Security teams should also consider implementing network-level protections and monitoring for unusual script execution patterns that might indicate exploitation attempts. The vulnerability serves as a critical reminder of how browser extensions can create attack vectors that bypass traditional web application security controls, emphasizing the need for robust extension security practices and continuous monitoring of browser security updates.