CVE-2017-5464 in Firefox
Summary
by MITRE
During DOM manipulations of the accessibility tree through script, the DOM tree can become out of sync with the accessibility tree, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.
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Analysis
by VulDB Data Team • 12/21/2020
This vulnerability represents a critical memory corruption issue that arises from inconsistencies between the Document Object Model and accessibility tree structures during dynamic DOM manipulation operations. The flaw occurs when JavaScript code performs operations that modify the DOM while simultaneously maintaining an accessibility tree representation that fails to properly synchronize with these changes. The root cause lies in the improper handling of tree synchronization mechanisms within the browser's rendering engine, specifically affecting Mozilla's Gecko layout engine that powers Firefox and Thunderbird applications.
The technical implementation of this vulnerability stems from a race condition or synchronization failure between DOM update operations and accessibility tree maintenance routines. When scripts manipulate DOM elements through methods such as element insertion, removal, or attribute modification, the accessibility tree that provides assistive technology support may retain references to stale or invalid memory locations. This desynchronization creates memory corruption conditions that can be exploited by malicious actors to execute arbitrary code with the privileges of the affected browser process. The vulnerability falls under the CWE-119 weakness category, specifically addressing improper access to memory locations and buffer overflows that occur due to inadequate bounds checking during tree structure modifications.
The operational impact of CVE-2017-5464 extends beyond simple browser instability, as it creates a potential attack vector for remote code execution in targeted environments. Attackers can craft malicious web pages that trigger specific DOM manipulation sequences, causing the browser to crash or execute unintended code when the corrupted accessibility tree is accessed. This vulnerability particularly affects older browser versions where memory management and synchronization mechanisms were less robust, making the exploitation more likely and the impact more severe. The affected versions include Thunderbird 52.1 and earlier, Firefox ESR versions 45.9 and 52.1, and Firefox versions before 53, all of which were widely deployed in enterprise and consumer environments, amplifying the potential attack surface.
Security mitigations for this vulnerability primarily involve immediate patching of affected browser versions to address the synchronization issues in DOM and accessibility tree handling. Organizations should prioritize updating to patched versions of Firefox ESR 45.9, Firefox ESR 52.1, Firefox 53, and Thunderbird 52.1, which contain fixes for the memory corruption issues. Browser hardening measures such as disabling JavaScript for untrusted sites, implementing content security policies, and using sandboxing mechanisms can provide additional protection layers. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and remote code execution through browser exploitation, with the attack surface being particularly relevant to web application security and enterprise browser management policies that require regular security updates and patch management protocols.