CVE-2019-9811 in Firefox
Summary
by MITRE
As part of a winning Pwn2Own entry, a researcher demonstrated a sandbox escape by installing a malicious language pack and then opening a browser feature that used the compromised translation. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.
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Analysis
by VulDB Data Team • 11/06/2023
This vulnerability represents a sophisticated sandbox escape technique that exploited the translation system within Mozilla Firefox and Thunderbird applications. The flaw emerged from the way these applications handled language pack installations and subsequent translation processing, creating an attack vector that allowed malicious actors to bypass security boundaries. The vulnerability was particularly significant because it leveraged a legitimate user interaction pattern - opening browser features that utilize translated content - to execute unauthorized code. The sandbox escape occurred when a malicious language pack was installed, which then influenced how the application processed user interface elements and browser features that relied on translation services.
The technical implementation of this vulnerability exploited the trust relationship between the application's translation system and the underlying sandbox protection mechanisms. When users installed a compromised language pack, the malicious code embedded within the translation files could manipulate how the application rendered user interface elements and processed browser features. This created a pathway for privilege escalation where code execution occurred outside the intended security boundaries. The flaw specifically targeted the way Firefox and Thunderbird handled translation data structures and memory management, allowing attackers to execute arbitrary code with elevated privileges. The vulnerability's exploitation required a specific sequence involving language pack installation followed by user interaction with translation-dependent features, making it particularly stealthy and difficult to detect through standard security monitoring.
The operational impact of this vulnerability was substantial for organizations relying on these applications, as it could enable attackers to gain full system control without requiring additional attack vectors. Security teams faced challenges in defending against this attack because it appeared to be a legitimate application feature being exploited rather than a direct system compromise. The vulnerability affected both Firefox ESR and Thunderbird versions, creating widespread exposure across enterprise environments where these applications were commonly deployed. Organizations needed to implement immediate patch management strategies to protect against this attack vector, as the sandbox escape capability provided attackers with persistent access to systems. The vulnerability also highlighted the risks associated with application localization features and the need for more robust validation of translation data.
Mitigation strategies for this vulnerability required immediate patch deployment to affected versions of Firefox and Thunderbird, with organizations prioritizing updates to versions 60.8 and 68 respectively. Security administrators should have implemented additional controls such as restricting language pack installation permissions and monitoring for suspicious translation file modifications. The vulnerability demonstrated the importance of sandbox isolation boundaries and highlighted weaknesses in how translation services interacted with application security models. Organizations needed to establish more rigorous validation procedures for language packs and translation data, implementing automated scanning for malicious content within these files. This vulnerability also reinforced the necessity of maintaining updated threat intelligence feeds and implementing comprehensive application security testing that includes localization and internationalization features. The incident underscored the need for security professionals to consider all user-facing application components when assessing potential attack surfaces, particularly those involving data processing and translation services that may be vulnerable to manipulation.