CVE-2012-3691 in iOS
Summary
by MITRE
WebKit in Apple Safari before 6.0 does not properly handle Cascading Style Sheets (CSS) property values, which allows remote attackers to bypass the Same Origin Policy via a crafted web site.
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Analysis
by VulDB Data Team • 01/04/2025
The vulnerability identified as CVE-2012-3691 represents a critical security flaw in Apple Safari's WebKit rendering engine that existed prior to version 6.0. This issue stems from improper handling of Cascading Style Sheets CSS property values, creating a significant bypass mechanism for the fundamental Same Origin Policy that governs web browser security. The Same Origin Policy serves as a cornerstone of web security by preventing scripts from one origin from accessing resources from another origin, thereby protecting users from cross-site scripting attacks and data theft. When this policy is circumvented, it opens pathways for malicious actors to exploit web applications and potentially access sensitive user data across different domains.
The technical flaw manifests through WebKit's insufficient validation of CSS property values that can be manipulated to create specific rendering behaviors. Attackers can craft malicious websites that exploit these CSS handling inconsistencies to bypass the security boundaries that normally separate different web origins. This vulnerability operates at the browser engine level rather than the application level, making it particularly dangerous because it undermines the core security architecture of the browser itself. The flaw allows for the execution of cross-origin requests that should normally be blocked by the browser's security model, effectively creating a backdoor for unauthorized data access and potential privilege escalation within the browser environment.
The operational impact of this vulnerability extends beyond simple data theft to encompass a wide range of potential attacks that leverage the bypassed security controls. Attackers could potentially access cookies, local storage, and other browser-based data that should remain isolated between different origins. This weakness enables sophisticated attacks such as cross-site scripting exploits, session hijacking, and data exfiltration from legitimate websites that users trust. The vulnerability particularly affects users of older Safari versions who may not have received automatic updates, creating a large attack surface across the user base. Organizations relying on Safari as their primary browser for web-based applications face significant risk exposure when users operate outdated browser versions.
Mitigation strategies for CVE-2012-3691 primarily focus on immediate browser updates to version 6.0 or later where Apple has implemented proper CSS property validation mechanisms. System administrators should enforce mandatory browser update policies and implement automated patch management systems to ensure all users operate on secure versions. Network security teams can deploy web application firewalls and content filtering solutions to detect and block suspicious CSS patterns that may indicate exploitation attempts. Additionally, users should be educated about the importance of keeping their browsers updated and should avoid visiting untrusted websites that may attempt to exploit this vulnerability. The remediation process should include comprehensive testing of web applications to verify that they no longer exhibit the insecure behavior associated with this CSS handling flaw, and security monitoring should be enhanced to detect potential exploitation attempts in real-time. This vulnerability aligns with CWE-200 (Information Exposure) and represents a classic example of how browser engine flaws can create persistent security risks that require immediate attention and remediation across affected systems.