CVE-2018-5110 in Firefox
Summary
by MITRE
If cursor visibility is toggled by script using from 'none' to an image and back through script, the cursor will be rendered temporarily invisible within Firefox. Note: This vulnerability only affects OS X. Other operating systems are not affected. This vulnerability affects Firefox < 58.
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Analysis
by VulDB Data Team • 07/20/2024
This vulnerability in Firefox represents a cursor visibility rendering issue that occurs specifically on macOS operating systems, affecting versions prior to 58. The flaw manifests when scripts toggle cursor visibility between 'none' and image states, creating a temporary invisibility state during the transition process. The technical implementation involves the browser's handling of cursor rendering states through JavaScript commands that manipulate the cursor's visibility property. This particular issue demonstrates how browser implementations can fail to properly manage visual state transitions, particularly in operating system-specific contexts where cursor handling differs from other platforms.
The vulnerability stems from improper state management within Firefox's rendering engine when processing cursor visibility changes through script execution. When a script sets cursor visibility to 'none' and subsequently to an image, the browser fails to maintain consistent visual representation during the transition phase, resulting in a brief period where the cursor appears invisible to users. This behavior creates potential security implications as users may be unable to locate their cursor during critical interactions, potentially leading to confusion or unintended actions. The issue specifically affects macOS due to differences in how the operating system handles cursor rendering compared to other platforms, making it a platform-specific implementation flaw rather than a universal browser vulnerability.
From an operational impact perspective, this vulnerability could compromise user experience and potentially create security risks in environments where precise cursor positioning is critical. Users may experience temporary loss of cursor visibility during script-driven cursor state changes, which could lead to usability issues or confusion during navigation. The vulnerability's platform specificity means that organizations running Firefox on macOS systems are at risk, while those using other operating systems remain unaffected. This limitation in scope reduces the overall attack surface but still represents a legitimate concern for macOS users of affected Firefox versions.
The technical implementation of this vulnerability aligns with CWE-124, which addresses "Copied Code with Improper Handling," and reflects improper handling of cursor state transitions in the browser's rendering pipeline. This flaw demonstrates how seemingly minor UI rendering issues can become security concerns when they affect user interaction and system usability. The vulnerability also relates to ATT&CK technique T1059, specifically the use of scripting languages for system manipulation, as it requires script execution to manifest. Users who employ scripts to control cursor visibility or implement custom UI elements on macOS systems are particularly vulnerable to this issue, as the transition between visibility states triggers the problematic behavior.
Mitigation strategies for this vulnerability include immediate upgrade to Firefox version 58 or later, which contains the necessary fixes for proper cursor state handling. System administrators should prioritize patch management for macOS environments where Firefox is deployed, ensuring that all users receive the security updates. Additionally, organizations should review scripts that manipulate cursor visibility properties to minimize the risk of triggering this behavior, particularly in automated or kiosk environments where cursor management is common. The fix implemented in Firefox 58 addresses the underlying rendering engine issue by properly synchronizing cursor state transitions and ensuring consistent visual representation throughout the visibility change process.