CVE-2012-4512 in Konqueror
Summary
by MITRE
The CSS parser (khtml/css/cssparser.cpp) in Konqueror in KDE 4.7.3 allows remote attackers to cause a denial of service (crash) and possibly read memory via a crafted font face source, related to "type confusion."
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Analysis
by VulDB Data Team • 09/23/2024
The vulnerability identified as CVE-2012-4512 resides within the CSS parser component of Konqueror web browser, specifically in the khtml/css/cssparser.cpp file within KDE 4.7.3 framework. This flaw represents a critical type confusion issue that manifests when the browser processes crafted font face source declarations in CSS stylesheets. The vulnerability exploits memory handling inconsistencies in how Konqueror interprets and processes font-related CSS properties, particularly those associated with the @font-face rule that defines custom fonts for web content rendering. The type confusion vulnerability occurs when the parser fails to properly validate data types during processing, leading to improper memory access patterns that can result in unpredictable behavior.
The technical exploitation of this vulnerability requires an attacker to craft a malicious CSS stylesheet containing specially formatted font face declarations that trigger the parser's type confusion mechanism. When Konqueror encounters such malformed input, the CSS parser attempts to process the font source specification using incorrect data type assumptions, causing memory corruption that ultimately results in application crash. This memory corruption can potentially be leveraged to read arbitrary memory locations, though the primary impact remains denial of service. The vulnerability demonstrates poor input validation and memory management practices within the KHTML rendering engine's CSS processing subsystem, where the parser does not adequately distinguish between different data types when handling font-related CSS properties.
The operational impact of CVE-2012-4512 extends beyond simple browser crashes, as it represents a potential vector for more sophisticated attacks within the context of web browsing. While the immediate effect is a denial of service that disrupts user experience and potentially provides attackers with information about memory layout, the underlying type confusion vulnerability could theoretically be exploited to achieve information disclosure or even arbitrary code execution depending on the memory corruption patterns. This vulnerability affects users of KDE 4.7.3 and potentially other versions of the Konqueror browser that utilize the same CSS parsing logic, making it a significant concern for organizations relying on KDE-based browsers for web access. The vulnerability is particularly concerning in environments where users may be exposed to untrusted web content, as it can be triggered through standard web browsing activities without requiring special privileges or user interaction beyond visiting a malicious website.
Mitigation strategies for CVE-2012-4512 should focus on immediate remediation through software updates, as the vulnerability was addressed in subsequent KDE releases that fixed the CSS parser implementation. System administrators should prioritize updating Konqueror and the KDE framework to versions that contain patched CSS parsing logic that properly handles type validation for font face declarations. Additionally, implementing web content filtering solutions and restricting access to untrusted websites can provide defense-in-depth measures against exploitation attempts. Organizations should also consider monitoring for potential exploitation attempts through network traffic analysis and implementing web application firewalls that can detect and block malicious CSS content. From a security standards perspective, this vulnerability aligns with CWE-457: Use of Uninitialized Variable and CWE-121: Stack-based Buffer Overflow, while the exploitation patterns may map to ATT&CK techniques involving privilege escalation and information gathering through memory corruption vulnerabilities. The incident underscores the importance of proper input validation and type safety in browser rendering engines, particularly in components responsible for parsing user-provided content.