CVE-2015-1256 in Chrome
Summary
by MITRE
Use-after-free vulnerability in the SVG implementation in Blink, as used in Google Chrome before 43.0.2357.65, allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted document that leverages improper handling of a shadow tree for a use element.
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Analysis
by VulDB Data Team • 05/19/2022
The vulnerability CVE-2015-1256 represents a critical use-after-free flaw within the Scalable Vector Graphics implementation of the Blink rendering engine, which powers Google Chrome browsers prior to version 43.0.2357.65. This issue resides in the handling of shadow tree structures specifically associated with use elements in SVG documents, creating a dangerous condition where memory previously freed by the browser's rendering engine can be accessed and manipulated by malicious actors. The vulnerability falls under the CWE-416 category of Use After Free, which is classified as a severe memory safety issue that can lead to arbitrary code execution or system compromise.
The technical exploitation of this vulnerability occurs when a crafted SVG document contains a use element that references another element within the same document or from an external source. During the rendering process, the Blink engine creates a shadow tree structure to manage the referenced elements, but fails to properly manage the lifecycle of memory associated with these structures. When the original element is destroyed or freed, the shadow tree may still maintain references to the freed memory locations, creating a scenario where subsequent operations can access invalid memory addresses. This improper memory management creates multiple attack vectors that can be leveraged by remote adversaries to execute malicious code or cause system instability.
The operational impact of CVE-2015-1256 extends beyond simple denial of service conditions to potentially enable arbitrary code execution on affected systems. Attackers can craft malicious SVG documents that, when loaded by vulnerable Chrome versions, trigger the use-after-free condition in memory management. This vulnerability is particularly dangerous because SVG documents can be embedded in web pages, delivered through email attachments, or hosted on compromised websites, allowing for widespread exploitation. The attack surface is broad since SVG support is enabled by default in most web browsers, and the vulnerability affects not only the browser itself but can also potentially compromise the underlying operating system through privilege escalation or code execution.
Mitigation strategies for CVE-2015-1256 require immediate browser updates to version 43.0.2357.65 or later, where Google implemented proper memory management fixes for the shadow tree handling in SVG elements. Organizations should also implement network-level protections such as content filtering systems that can detect and block suspicious SVG content, particularly those containing complex use element references. Additionally, browser hardening measures including sandboxing, privilege separation, and strict content security policies should be enforced to limit the potential impact of successful exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving code injection and privilege escalation, with the initial compromise often occurring through web-based attack vectors that align with T1059 and T1068 tactics. The vulnerability demonstrates the importance of memory safety in browser engines and the critical need for regular security updates to address such fundamental implementation flaws that can compromise entire computing environments.