CVE-2013-1054 in unity-firefox-extension
Summary
by MITRE • 04/08/2021
The unity-firefox-extension package could be tricked into destroying the Unity webapps context, causing Firefox to crash. This could be achieved by spinning the event loop inside the webapps initialization callback. Fixed in 3.0.0+14.04.20140416-0ubuntu1.14.04.1 by shipping an empty package, thus disabling the extension entirely.
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Analysis
by VulDB Data Team • 04/11/2021
The vulnerability described in CVE-2013-1054 resides within the unity-firefox-extension package, which represents a Firefox add-on designed to integrate web applications with the Ubuntu Unity desktop environment. This extension was intended to enable seamless interaction between Firefox and Unity's webapps framework, allowing users to launch web applications directly from the desktop shell. However, the implementation contained a critical flaw that could be exploited to compromise the stability of the Firefox browser through controlled manipulation of the webapps initialization process.
The technical flaw manifests through a specific manipulation of the event loop within the webapps initialization callback mechanism. When an attacker crafts malicious content that triggers this callback, they can cause the extension to enter an infinite loop or otherwise consume excessive resources during the initialization phase. This particular vulnerability falls under the category of improper control flow management and represents a classic example of a resource exhaustion attack vector. The flaw essentially allows an attacker to manipulate the extension's execution path in a way that disrupts normal program flow and causes the Firefox browser to crash or become unresponsive.
The operational impact of this vulnerability extends beyond simple browser instability, as it represents a potential denial-of-service vector that could be exploited by malicious actors to disrupt user productivity or serve as a stepping stone for more sophisticated attacks. When Firefox crashes due to this extension manipulation, users lose access to their browsing session and may experience data loss. The vulnerability specifically targets the Unity desktop environment's integration layer, making it particularly concerning for Ubuntu users who rely heavily on this desktop framework. The attack surface is limited to systems running the vulnerable unity-firefox-extension package, but the potential for exploitation remains significant given the widespread adoption of Ubuntu and its Unity interface.
The fix implemented by the Ubuntu security team involved a complete removal of the vulnerable extension functionality through the deployment of an empty package version 3.0.0+14.04.20140416-0ubuntu1.14.04.1. This approach effectively disables the extension entirely by replacing it with a minimal package that contains no functional code. This mitigation strategy aligns with the principle of least privilege and demonstrates a proactive approach to addressing security vulnerabilities that cannot be easily patched without introducing further instability. The solution represents a pragmatic response to the issue, prioritizing system stability over functionality, which is often the appropriate course of action when dealing with core desktop integration components that have proven to be inherently unstable. This vulnerability and its resolution exemplify the challenges of maintaining security in desktop integration frameworks where complex interactions between different software layers can create unexpected attack vectors. The incident also highlights the importance of proper input validation and event loop management in browser extensions, as deficiencies in these areas can lead to serious stability and security consequences. From a cybersecurity perspective, this vulnerability demonstrates how seemingly minor implementation flaws in desktop integration components can have significant impacts on overall system reliability and user experience, particularly in environments where multiple software layers interact closely to provide a unified user interface experience.