CVE-2019-11697 in Firefox
Summary
by MITRE
If the ALT and "a" keys are pressed when users receive an extension installation prompt, the extension will be installed without the install prompt delay that keeps the prompt visible in order for users to accept or decline the installation. A malicious web page could use this with spoofing on the page to trick users into installing a malicious extension. This vulnerability affects Firefox < 67.
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Analysis
by VulDB Data Team • 06/06/2024
This vulnerability represents a critical user interface interaction flaw that undermines the security model of Firefox's extension installation process. The issue stems from an improper handling of keyboard input during extension installation prompts, specifically when users simultaneously press the ALT key and the "a" key. Under normal circumstances, Firefox implements a deliberate delay mechanism that ensures extension installation prompts remain visible for user confirmation before proceeding with installation. This design element serves as a crucial security control that prevents automatic installation of extensions without explicit user consent.
The technical flaw occurs at the input handling layer where the combination of ALT and "a" keys bypasses the standard prompt delay mechanism. This keyboard shortcut combination effectively triggers an immediate installation action, circumventing the intended user interaction sequence. The vulnerability creates a race condition between user input detection and the installation process, allowing for rapid execution of installation commands without proper user awareness. This behavior aligns with CWE-284 access control vulnerabilities, specifically those involving insufficient user consent mechanisms in security-critical operations.
The operational impact of this vulnerability extends beyond simple bypass of installation prompts. Attackers can leverage this flaw in conjunction with sophisticated social engineering techniques to create convincing spoofed web pages that appear legitimate while automatically installing malicious extensions. The vulnerability affects Firefox versions prior to 67, representing a significant window of exposure where users were particularly vulnerable to automated attacks. This weakness directly enables malicious actors to exploit user trust in familiar interface elements, transforming what should be a security-conscious interaction into an automatic installation process.
The security implications of this vulnerability align with several ATT&CK framework techniques including T1176 for Browser Extensions and T1059 for Command and Scripting Interpreter. Attackers can use this vulnerability to establish persistent access through malicious extensions that automatically install without user knowledge. The flaw essentially removes the user's ability to make informed decisions about extension installation, which is fundamental to maintaining browser security boundaries. Organizations and users should prioritize immediate patching to address this vulnerability, as it represents a direct threat to browser security integrity and user control over software installation processes.
This vulnerability demonstrates the critical importance of proper input validation and user interaction handling in security-sensitive applications. The flaw illustrates how seemingly minor keyboard shortcut combinations can have significant security implications when they bypass established security controls. The remediation involves implementing proper input filtering mechanisms that prevent specific key combinations from triggering automatic installation actions while maintaining legitimate user functionality. The incident underscores the need for comprehensive testing of user interaction flows in security-critical applications to identify potential bypass mechanisms that could be exploited by malicious actors.