CVE-2015-1287 in Chrome
Summary
by MITRE
Blink, as used in Google Chrome before 44.0.2403.89, enables a quirks-mode exception that limits the cases in which a Cascading Style Sheets (CSS) document is required to have the text/css content type, which allows remote attackers to bypass the Same Origin Policy via a crafted web site, related to core/fetch/CSSStyleSheetResource.cpp.
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Analysis
by VulDB Data Team • 06/03/2022
The vulnerability identified as CVE-2015-1287 resides within the Blink rendering engine that powers Google Chrome and other web browsers. This flaw represents a significant security issue that undermines the fundamental Same Origin Policy mechanism designed to prevent unauthorized cross-origin resource access. The vulnerability specifically affects Chrome versions prior to 44.0.2403.89, where the implementation of quirks-mode exceptions in CSS processing creates an exploitable gap in content type validation. The core issue is located in the core/fetch/CSSStyleSheetResource.cpp file, which handles CSS resource fetching and processing within the browser's networking stack.
The technical flaw exploits a quirk in the CSS processing logic that allows certain CSS documents to bypass the standard requirement for text/css content type validation. In normal operation, web browsers enforce strict content type checking to ensure that CSS resources are properly formatted and originate from trusted sources. However, this vulnerability enables attackers to craft malicious web pages that present CSS content with non-standard content types while still being processed by the browser's CSS engine. The quirks-mode exception creates a pathway where the browser's security boundaries can be circumvented, allowing remote attackers to inject and execute malicious CSS code that could potentially access resources from different origins.
This vulnerability has severe operational implications for web security as it directly enables cross-origin resource access bypass attacks. Attackers can leverage this flaw to construct malicious websites that load CSS content from different domains without proper origin validation, potentially accessing sensitive data or performing unauthorized operations. The exploitation scenario involves creating a web page that serves CSS content with modified content types, which then gets processed by the vulnerable browser engine. This could lead to information disclosure, session hijacking, or other malicious activities that compromise user security and privacy. The vulnerability affects not only individual users but also enterprise environments where Chrome is widely deployed, making it a critical concern for security administrators.
The attack vector demonstrates how seemingly minor implementation details in browser security can create significant vulnerabilities. This flaw aligns with CWE-200, which addresses "Information Exposure Through Output with Sensitive Information," and relates to ATT&CK technique T1059.006 for "Command and Scripting Interpreter: JavaScript" as it enables unauthorized script execution through CSS manipulation. Organizations should implement immediate mitigations including updating to Chrome version 44.0.2403.89 or later, which contains the patched implementation that properly enforces content type validation. Additionally, security teams should monitor for any related vulnerabilities in similar browser engines and ensure comprehensive patch management processes are in place. The vulnerability underscores the importance of strict content validation and the potential risks associated with browser engine quirks that may inadvertently weaken security boundaries.