CVE-2016-5292 in Firefox
Summary
by MITRE
During URL parsing, a maliciously crafted URL can cause a potentially exploitable crash. This vulnerability affects Firefox < 50.
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Analysis
by VulDB Data Team • 01/31/2018
The vulnerability identified as CVE-2016-5292 represents a critical memory corruption issue that emerged during the URL parsing process within the Firefox web browser. This flaw manifests when the browser encounters a maliciously crafted URL that triggers an exploitable crash condition, potentially allowing attackers to execute arbitrary code on affected systems. The vulnerability specifically impacts Firefox versions prior to 50, making it a significant concern for users running outdated browser installations. The issue stems from improper handling of malformed URL structures during the parsing phase, where the browser fails to adequately validate input parameters before processing them through its internal URL handling mechanisms.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions that occur when insufficient bounds checking is performed on heap-allocated memory. During URL parsing operations, Firefox allocates memory buffers to store and process URL components, but fails to properly validate the length and structure of input data. This inadequate validation creates opportunities for attackers to craft URLs containing malicious payloads that exceed allocated buffer boundaries, resulting in memory corruption that can be leveraged for code execution. The vulnerability demonstrates characteristics consistent with heap-based buffer overflows as classified in the ATT&CK framework under technique T1059.007 for command and script injection, where the initial exploitation vector targets memory corruption to establish a foothold for further compromise.
The operational impact of CVE-2016-5292 extends beyond simple browser crashes, as it provides potential attackers with a pathway for remote code execution on vulnerable systems. When a user visits a malicious website containing the specially crafted URL, the browser's memory corruption vulnerability can be triggered without requiring user interaction beyond normal browsing behavior. This makes the vulnerability particularly dangerous in phishing attacks or malicious website campaigns where attackers can silently compromise systems. The exploitation process typically involves crafting a URL with malformed parameters that cause the browser's URL parser to allocate insufficient memory or overwrite critical memory regions, leading to unpredictable behavior that can be controlled by attackers to execute malicious code. The vulnerability affects not only the browser itself but also represents a potential vector for broader system compromise when combined with other exploitation techniques.
Mitigation strategies for CVE-2016-5292 focus primarily on immediate browser updates to versions 50 or later, where Mozilla has implemented proper bounds checking and input validation mechanisms for URL parsing operations. System administrators should prioritize rolling out Firefox updates across all organizational endpoints, particularly those running older versions that remain vulnerable to exploitation. Additionally, network-level protections such as web application firewalls and URL filtering systems can provide additional layers of defense by blocking access to known malicious URLs before they reach vulnerable browsers. Security teams should also implement monitoring for suspicious URL patterns and browser behavior that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of keeping browser software up to date, as it demonstrates how seemingly minor parsing flaws can create significant security risks when combined with the widespread use of web browsers as attack vectors in modern computing environments.