CVE-2022-1529 in Firefox
Summary
by MITRE • 12/22/2022
An attacker could have sent a message to the parent process where the contents were used to double-index into a JavaScript object, leading to prototype pollution and ultimately attacker-controlled JavaScript executing in the privileged parent process. This vulnerability affects Firefox ESR < 91.9.1, Firefox < 100.0.2, Firefox for Android < 100.3.0, and Thunderbird < 91.9.1.
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Analysis
by VulDB Data Team • 05/01/2025
This vulnerability represents a critical prototype pollution flaw in Mozilla Firefox and Thunderbird browsers that enables remote code execution in privileged contexts. The issue stems from improper handling of message passing between child and parent processes, specifically when JavaScript objects are manipulated through double-indexing operations that can corrupt object prototypes. The vulnerability affects multiple Mozilla products including Firefox Extended Support Release versions prior to 91.9.1, standard Firefox versions before 100.0.2, Firefox for Android versions before 100.3.0, and Thunderbird versions before 91.9.1. The flaw occurs during inter-process communication where maliciously crafted messages can exploit the prototype chain manipulation to gain elevated privileges.
The technical implementation of this vulnerability involves a specific pattern of message handling where attacker-controlled data flows through the parent process and gets processed through JavaScript object operations that allow prototype pollution. When a message containing malicious data is sent to the parent process, the system performs double-indexing operations on JavaScript objects that can modify the prototype chain of objects. This prototype pollution enables attackers to inject malicious code into the privileged parent process context, effectively bypassing security boundaries between processes. The vulnerability is classified under CWE-471 as "Modification of Assumed-Immutable Data" and represents a sophisticated form of prototype pollution that leverages process isolation weaknesses.
The operational impact of this vulnerability is severe as it allows attackers to execute arbitrary JavaScript code with elevated privileges in the parent process context. This creates a significant attack surface where malicious actors can bypass sandboxing mechanisms and gain access to sensitive functionality that should only be available to trusted processes. The exploitation chain typically involves sending specially crafted messages through the message passing interface, manipulating object prototypes to inject malicious properties, and then leveraging these injected properties to execute code in the privileged context. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1059.007 for JavaScript and T1068 for locally executed commands, with the prototype pollution aspect aligning with T1211 for privilege escalation through code injection.
Mitigation strategies for this vulnerability involve updating to the patched versions of affected Mozilla products as soon as possible, implementing strict message validation and sanitization in inter-process communication channels, and applying additional process isolation measures. Organizations should also consider implementing network-level protections such as content filtering and monitoring for suspicious message patterns, while security teams should closely monitor for exploitation attempts. The patch addresses the root cause by properly validating message contents and preventing prototype chain modifications during object indexing operations, ensuring that attacker-controlled data cannot influence prototype properties of objects used in privileged contexts. Additionally, browser hardening measures including stricter Content Security Policy implementations and enhanced sandboxing configurations can provide additional defense layers against similar exploitation patterns.