CVE-2015-4507 in Firefox
Summary
by MITRE
The SavedStacks class in the JavaScript implementation in Mozilla Firefox before 41.0, when the Debugger API is enabled, allows remote attackers to cause a denial of service (getSlotRef assertion failure and application exit) or possibly execute arbitrary code via a crafted web site.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/19/2022
The vulnerability identified as CVE-2015-4507 represents a critical security flaw within the JavaScript engine of Mozilla Firefox versions prior to 41.0. This issue resides in the SavedStacks class implementation and specifically manifests when the Debugger API is enabled, creating a dangerous attack surface that could be exploited by remote adversaries. The vulnerability stems from improper handling of stack frame references within the JavaScript execution environment, particularly when debugging functionality is active. The flaw enables attackers to manipulate internal JavaScript engine structures through carefully crafted web content, potentially leading to system instability or unauthorized code execution.
The technical implementation of this vulnerability involves an assertion failure within the getSlotRef method of the SavedStacks class, which occurs when the Debugger API is actively used. This assertion failure represents a fundamental breakdown in the JavaScript engine's memory management and stack frame handling mechanisms. When attackers construct malicious web pages that trigger specific conditions within the Debugger API, the engine's internal consistency checks fail, resulting in either application termination or more severe memory corruption that could enable arbitrary code execution. The vulnerability specifically targets the JavaScript engine's internal data structures and memory management systems, making it particularly dangerous as it operates at a low level within the browser's core execution environment.
From an operational perspective, this vulnerability presents significant risk to Firefox users as it can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious website. The denial of service aspect of this vulnerability means that legitimate users could experience unexpected browser crashes or application exits, while the potential for arbitrary code execution creates a much more serious threat that could allow attackers to compromise user systems completely. The impact extends beyond individual user sessions as this vulnerability affects the browser's core JavaScript engine functionality, potentially enabling attackers to bypass security boundaries and execute malicious code with the privileges of the browser process. The vulnerability's exploitation requires the Debugger API to be enabled, which is typically available in development environments or when specific debugging tools are active, but it can also be triggered through JavaScript code that enables debugging functionality programmatically.
Security mitigations for CVE-2015-4507 primarily involve upgrading to Firefox version 41.0 or later, which contains the necessary patches to address the assertion failure in the SavedStacks class. Organizations should prioritize immediate deployment of this security update across all affected systems to eliminate the risk of exploitation. Additionally, administrators can implement browser security policies that disable the Debugger API in production environments where it is not required for legitimate debugging purposes. The vulnerability aligns with CWE-119, which addresses memory corruption issues in software implementations, and represents a classic example of a buffer overflow or memory management flaw that can lead to arbitrary code execution. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and code execution through browser-based attacks, specifically targeting the execution of malicious JavaScript code within the browser's trusted execution environment. Organizations should also consider implementing network-based security controls such as web application firewalls and content filtering systems to detect and block potentially malicious web content that could exploit this vulnerability.