CVE-2015-1218 in Chrome
Summary
by MITRE
Multiple use-after-free vulnerabilities in the DOM implementation in Blink, as used in Google Chrome before 41.0.2272.76, allow remote attackers to cause a denial of service or possibly have unspecified other impact via vectors that trigger movement of a SCRIPT element to different documents, related to (1) the HTMLScriptElement::didMoveToNewDocument function in core/html/HTMLScriptElement.cpp and (2) the SVGScriptElement::didMoveToNewDocument function in core/svg/SVGScriptElement.cpp.
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Analysis
by VulDB Data Team • 04/12/2022
The vulnerability identified as CVE-2015-1218 represents a critical use-after-free flaw within the Document Object Model implementation of the Blink rendering engine that powers Google Chrome. This issue affects versions prior to 41.0.2272.76 and stems from improper memory management during document transitions involving script elements. The vulnerability manifests when SCRIPT elements are moved between different documents, creating conditions where freed memory locations are subsequently accessed, leading to potential system instability and arbitrary code execution risks.
The technical implementation of this vulnerability involves two primary code paths within the Blink engine's core components. The first vulnerability occurs in the HTMLScriptElement::didMoveToNewDocument function located in core/html/HTMLScriptElement.cpp, while the second exists in the SVGScriptElement::didMoveToNewDocument function found in core/svg/SVGScriptElement.cpp. These functions handle the movement of script elements between documents and fail to properly manage memory references when such transitions occur. When a SCRIPT element is moved from one document context to another, the original memory allocation may be freed while references to that memory persist, creating a use-after-free condition that can be exploited by remote attackers.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as indicated by the unspecified other impacts mentioned in the CVE description. Attackers can potentially leverage these use-after-free conditions to execute arbitrary code on affected systems, making this a serious security concern. The vulnerability's remote exploitability means that malicious actors can trigger these conditions through web-based attacks without requiring user interaction beyond visiting a compromised website. The memory corruption resulting from these use-after-free conditions can lead to unpredictable behavior including crashes, data corruption, or more dangerous scenarios where attackers might inject and execute malicious code within the browser's memory space.
This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations, and demonstrates how improper memory management can create persistent security risks in complex browser environments. The attack surface is particularly concerning given Chrome's widespread adoption and the potential for these vulnerabilities to be exploited in phishing campaigns, drive-by downloads, or other web-based attack vectors. The fact that this affects both standard HTML script elements and SVG script elements indicates a systemic issue within the Blink engine's document transition handling mechanisms, suggesting that similar patterns may exist in other parts of the codebase.
Mitigation strategies for CVE-2015-1218 primarily involve immediate patching of affected Chrome versions to 41.0.2272.76 or later, which contains the necessary memory management fixes. Organizations should also implement network-level protections such as web application firewalls and content filtering systems to reduce exposure to potentially malicious websites. Browser hardening measures including sandboxing, strict content security policies, and regular security updates form essential components of defense-in-depth strategies. Additionally, security monitoring should include detection of unusual browser behavior patterns that might indicate exploitation attempts, and incident response procedures should be prepared to handle potential compromise scenarios arising from these memory corruption vulnerabilities. The vulnerability serves as a reminder of the critical importance of memory safety in browser implementations and the potential for seemingly benign operations like document transitions to create serious security risks when proper memory management is not implemented.