CVE-2014-1540 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsEventListenerManager::CompileEventHandlerInternal function in the Event Listener Manager in Mozilla Firefox before 30.0 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via crafted web content.
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Analysis
by VulDB Data Team • 06/22/2021
The vulnerability identified as CVE-2014-1540 represents a critical use-after-free flaw within Mozilla Firefox's event handling infrastructure. This vulnerability exists in the nsEventListenerManager::CompileEventHandlerInternal function, which is responsible for managing event listeners in the browser's rendering engine. The flaw arises when the browser processes crafted web content that triggers improper memory management during event handler compilation, creating conditions where freed memory can be accessed and manipulated by malicious code.
The technical implementation of this vulnerability stems from inadequate memory management practices within Firefox's JavaScript event system. When the browser encounters malformed event listener declarations or complex event handler compositions, the CompileEventHandlerInternal function fails to properly track memory references, leading to scenarios where memory blocks are deallocated while still being referenced by active event handlers. This memory corruption creates exploitable conditions that can be leveraged by remote attackers to execute arbitrary code with the privileges of the browser process.
From an operational perspective, this vulnerability poses significant risks to users browsing the web, as it can be triggered through standard web content without requiring user interaction beyond visiting a malicious website. The heap memory corruption resulting from this use-after-free condition can lead to either remote code execution or denial of service attacks, making it particularly dangerous for enterprise environments where users may encounter untrusted web content. The vulnerability affects Firefox versions prior to 30.0, representing a substantial attack surface for threat actors targeting browser-based exploits.
The exploitability of this vulnerability aligns with common attack patterns documented in the ATT&CK framework under the technique of "Exploitation for Code Execution" and "Memory Corruption" threats. This flaw demonstrates characteristics consistent with CWE-416, which describes "Use After Free" conditions in software systems, where programs access memory after it has been freed. The vulnerability's impact is amplified by Firefox's widespread adoption and the fact that it requires no special privileges or user interaction to trigger, making it an attractive target for automated exploitation campaigns and zero-day attacks.
Organizations and users should immediately update to Firefox version 30.0 or later to mitigate this vulnerability, as the patch addresses the underlying memory management issues in the event listener compilation process. Additional mitigations include implementing content security policies, using browser sandboxing features, and maintaining awareness of emerging exploitation techniques targeting similar memory corruption vulnerabilities in web browsers. Security teams should also monitor for indicators of compromise related to this vulnerability and consider implementing network-based detection measures to identify potential exploitation attempts.