CVE-2016-5266 in Firefox
Summary
by MITRE
Mozilla Firefox before 48.0 does not properly restrict drag-and-drop (aka dataTransfer) actions for file: URIs, which allows user-assisted remote attackers to access local files via a crafted web site.
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Analysis
by VulDB Data Team • 10/09/2024
The vulnerability identified as CVE-2016-5266 represents a significant security flaw in Mozilla Firefox versions prior to 48.0, specifically concerning the handling of drag-and-drop operations involving file system URIs. This weakness stems from insufficient restrictions on dataTransfer actions when dealing with file: URIs, creating an avenue for malicious actors to exploit user interactions with crafted web content. The flaw operates at the intersection of web browser security boundaries and file system access controls, potentially allowing unauthorized file disclosure when users interact with malicious websites.
The technical implementation of this vulnerability involves the improper handling of drag-and-drop events within Firefox's web rendering engine. When users drag files from their local system onto web pages, the browser's dataTransfer object should enforce strict security policies to prevent unauthorized access to local file system resources. However, Firefox versions before 48.0 failed to adequately validate these operations, particularly when file: URIs were involved. This oversight allows attackers to construct malicious web pages that can intercept and potentially access file system contents through crafted drag-and-drop interactions, effectively bypassing normal browser security restrictions that should prevent such cross-domain file access.
From an operational perspective, this vulnerability creates a user-assisted attack vector that requires minimal technical expertise to exploit. Attackers can craft malicious websites that present seemingly benign drag-and-drop interfaces while silently accessing local files from victims' systems. The impact extends beyond simple information disclosure, as attackers could potentially access sensitive documents, configuration files, or personal data stored locally on compromised systems. This vulnerability particularly affects users who frequently interact with web content and may inadvertently drag files onto malicious pages, making it a significant concern for both individual users and enterprise environments where sensitive data may be present.
The security implications of CVE-2016-5266 align with CWE-200, which addresses improper restriction of information leakage, and can be categorized under ATT&CK technique T1056.001 for Input Injection. The vulnerability demonstrates a classic case of insufficient input validation and improper access control in web browser components. Organizations should prioritize immediate patching of affected Firefox installations to mitigate this risk, as the vulnerability exists in the core browser functionality and can be exploited without requiring special privileges or complex attack chains. The remediation process involves upgrading to Firefox 48.0 or later versions where proper restrictions on file: URI drag-and-drop operations have been implemented, effectively closing this security gap and restoring the expected isolation between web content and local file system access.