CVE-2013-6623 in Chrome
Summary
by MITRE
The SVG implementation in Blink, as used in Google Chrome before 31.0.1650.48, allows remote attackers to cause a denial of service (out-of-bounds read) by leveraging the use of tree order, rather than transitive dependency order, for layout.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 06/02/2021
The vulnerability identified as CVE-2013-6623 represents a critical out-of-bounds read flaw within the SVG rendering engine of Blink, the web browser engine that powers Google Chrome. This issue specifically manifests when processing Scalable Vector Graphics content, where the engine's layout algorithm incorrectly handles the tree traversal order during rendering operations. The flaw stems from a fundamental mismanagement of dependency relationships within the document object model, creating a scenario where the rendering process accesses memory locations beyond the intended boundaries of SVG elements.
The technical implementation of this vulnerability exploits the difference between tree order traversal and transitive dependency order in the layout engine's processing logic. When Chrome processes SVG content, it maintains a hierarchical representation of elements that must be rendered in a specific sequence to ensure proper visual output. However, the Blink engine's implementation fails to correctly account for the transitive dependencies between elements, instead relying on a simpler tree order approach that can lead to accessing invalid memory addresses. This misalignment creates a predictable pattern where malicious SVG content can force the browser to read beyond allocated memory boundaries, resulting in a crash or potentially more severe consequences.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential pathway for more sophisticated attacks. An attacker could craft malicious SVG files that, when loaded in affected Chrome versions, would trigger the out-of-bounds read condition and cause the browser to crash or behave unpredictably. This vulnerability aligns with CWE-129, which describes improper validation of array indices, and demonstrates how improper handling of object relationships can lead to memory safety issues. The attack surface is particularly concerning given that SVG content is commonly embedded in web pages, making this vulnerability exploitable through standard web browsing activities.
The exploitation of this vulnerability requires an attacker to craft SVG content that specifically triggers the problematic code path in Blink's layout engine. The attack vector is primarily through web-based content delivery, where a malicious actor could host compromised SVG files on web servers or embed them within compromised websites. This creates a scenario where users browsing to affected sites could be automatically exploited without requiring any additional user interaction beyond normal web browsing. The vulnerability's classification under ATT&CK technique T1203, which covers "Exploitation for Client Execution," demonstrates how this flaw could enable broader attack chains. The lack of input validation and proper boundary checking in the SVG processing pipeline creates multiple opportunities for exploitation, particularly in environments where users might encounter untrusted SVG content.
Mitigation strategies for CVE-2013-6623 primarily focus on updating to patched versions of Google Chrome, specifically versions 31.0.1650.48 and later, where the layout engine's handling of SVG elements has been corrected. Additionally, organizations should implement network-level controls to filter or block suspicious SVG content, particularly when such content originates from untrusted sources. Browser security configurations should be reviewed to ensure that SVG processing is properly restricted, and regular patch management procedures should be enforced to maintain up-to-date browser versions. The vulnerability serves as a reminder of the importance of proper memory management in web browser engines and highlights the need for comprehensive testing of layout and rendering algorithms to prevent similar issues in the future.