CVE-2010-5074 in SeaMonkey
Summary
by MITRE
The layout engine in Mozilla Firefox before 4.0, Thunderbird before 3.3, and SeaMonkey before 2.1 executes different code for visited and unvisited links during the processing of Cascading Style Sheets (CSS) token sequences, which makes it easier for remote attackers to obtain sensitive information about visited web pages via a timing attack.
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Analysis
by VulDB Data Team • 11/27/2021
The vulnerability described in CVE-2010-5074 represents a significant information disclosure flaw in the rendering engines of several Mozilla applications including Firefox, Thunderbird, and SeaMonkey. This issue stems from the inconsistent handling of CSS token sequences between visited and unvisited hyperlinks within the browser's layout engine. The fundamental problem lies in how these applications process and render hyperlink elements, creating observable differences in processing behavior that can be exploited by malicious actors.
The technical implementation of this vulnerability exploits the timing differences that occur when the browser processes CSS rules for visited versus unvisited links. When a web page contains CSS selectors that differentiate between visited and unvisited hyperlinks, the browser's rendering engine executes distinct code paths for each state. This divergence creates measurable timing variations that can be detected and analyzed by attackers. The flaw specifically manifests during the CSS token processing phase where the browser's layout engine handles the interpretation and application of CSS rules to hyperlink elements.
From an operational perspective, this vulnerability enables remote attackers to perform timing attacks that can reveal whether a user has previously visited specific web pages. The attack works by measuring the time differences required to process CSS rules for different hyperlink states, allowing an attacker to infer browsing history through careful observation of these timing discrepancies. This information disclosure can be particularly damaging as it allows attackers to discover sensitive user behavior patterns, potentially revealing personal interests, browsing habits, or even confidential information access patterns.
The security implications extend beyond simple information disclosure, as this vulnerability can be leveraged as part of broader reconnaissance activities. Attackers can use the timing differences to map out user navigation patterns and potentially correlate this information with other data sources. This type of attack falls under the category of side-channel information disclosure attacks and aligns with attack patterns documented in the attack tree framework. The vulnerability demonstrates how seemingly benign CSS processing can become a vector for privacy violations and information leakage.
This vulnerability maps to CWE-203: "Observable Behavioral Vulnerability" and represents a classic example of how application behavior differences can create security risks. The issue is particularly concerning because it operates at the browser engine level, affecting the fundamental rendering process that users interact with daily. The attack requires minimal privileges and can be executed through standard web page content, making it highly exploitable in real-world scenarios. Security professionals should consider this vulnerability when assessing browser security configurations and implementing defense-in-depth strategies.
Mitigation strategies for CVE-2010-5074 require immediate application of vendor patches and updates to the affected Mozilla products. Users should ensure their browsers are updated to versions that address this timing discrepancy issue. Organizations should also consider implementing network-level monitoring to detect potential exploitation attempts and establish policies for regularly updating browser software. The vulnerability highlights the importance of consistent code execution paths in security-sensitive applications and underscores the need for careful attention to timing behavior in web rendering engines. Additionally, browser vendors should implement more robust mechanisms to prevent timing-based information leakage while maintaining the expected functionality of CSS hyperlink handling.