CVE-2012-4201 in Firefox
Summary
by MITRE
The evalInSandbox implementation in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 uses an incorrect context during the handling of JavaScript code that sets the location.href property, which allows remote attackers to conduct cross-site scripting (XSS) attacks or read arbitrary files by leveraging a sandboxed add-on.
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Analysis
by VulDB Data Team • 10/22/2024
The vulnerability identified as CVE-2012-4201 represents a critical security flaw in the JavaScript sandboxing mechanisms of Mozilla Firefox and related applications. This issue specifically affects the evalInSandbox implementation which is designed to provide isolated execution environments for untrusted code, particularly within add-on contexts. The flaw manifests when JavaScript code attempts to manipulate the location.href property, creating a dangerous context switching scenario that undermines the fundamental security boundaries intended by the sandbox architecture.
The technical root cause of this vulnerability lies in the improper handling of JavaScript execution contexts within the sandbox environment. When code executes within a sandboxed add-on and attempts to modify the location.href property, the system fails to maintain proper context isolation. This context switching vulnerability allows malicious JavaScript code to escape the intended sandbox boundaries and gain access to privileged operations. The flaw specifically impacts versions of Firefox prior to 17.0, Firefox ESR 10.x prior to 10.0.11, Thunderbird prior to 17.0, Thunderbird ESR 10.x prior to 10.0.11, and SeaMonkey prior to 2.14, indicating a widespread issue affecting multiple Mozilla products.
The operational impact of this vulnerability is severe and multifaceted, enabling attackers to execute cross-site scripting attacks that can compromise user sessions and steal sensitive information. The ability to read arbitrary files through this vulnerability creates additional attack vectors where malicious actors can access local system resources that should remain protected from sandboxed code execution. This flaw essentially allows attackers to bypass the core security model of the browser's add-on system, potentially enabling full system compromise through carefully crafted malicious add-ons or web pages that leverage this sandbox escape mechanism.
Security researchers have classified this vulnerability under CWE-20, which describes improper input validation, and it aligns with ATT&CK techniques related to privilege escalation and sandbox evasion. The vulnerability demonstrates how seemingly isolated execution environments can be compromised through improper context management in JavaScript engines. Organizations affected by this vulnerability should prioritize immediate patching of all impacted versions, as the attack surface includes not only web browsing but also email clients and browser applications that utilize the same underlying JavaScript sandboxing technology. The remediation process requires updating to patched versions of Firefox, Thunderbird, and SeaMonkey, with particular attention to the Firefox ESR releases that were also affected by this critical flaw.
The broader implications of this vulnerability extend beyond immediate exploitation capabilities to highlight the complexity of modern browser security architectures. This flaw demonstrates that even sophisticated sandboxing implementations can contain critical design flaws that undermine security assumptions. The vulnerability serves as a reminder of the importance of thorough security testing for sandboxed execution environments, particularly when dealing with dynamic language features such as JavaScript's eval functionality and property manipulation capabilities. Organizations should implement additional monitoring and detection mechanisms to identify potential exploitation attempts, while security teams must ensure comprehensive testing of all browser security features, especially those involving dynamic code execution and context switching operations.