CVE-2015-6777 in Chrome
Summary
by MITRE
Use-after-free vulnerability in the ContainerNode::notifyNodeInsertedInternal function in WebKit/Source/core/dom/ContainerNode.cpp in the DOM implementation in Google Chrome before 47.0.2526.73 allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors related to DOMCharacterDataModified events for certain detached-subtree insertions.
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Analysis
by VulDB Data Team • 06/28/2022
The CVE-2015-6777 vulnerability represents a critical use-after-free flaw within the WebKit rendering engine's DOM implementation that affected Google Chrome versions prior to 47.0.2526.73. This vulnerability resides in the ContainerNode::notifyNodeInsertedInternal function located in WebKit/Source/core/dom/ContainerNode.cpp, which governs how nodes are managed within the Document Object Model structure. The flaw manifests when processing DOMCharacterDataModified events during specific detached-subtree insertion operations, creating a scenario where memory that has been freed is still accessed by subsequent operations.
The technical nature of this vulnerability stems from improper memory management during DOM node operations, specifically when a node is removed from the document tree but remains referenced in event handlers or other internal structures. When a detached subtree undergoes insertion operations while DOMCharacterDataModified events are being processed, the system attempts to access memory locations that have already been deallocated. This memory access violation creates a use-after-free condition that can be exploited by remote attackers to trigger unpredictable behavior in the browser's memory management system. The vulnerability operates under CWE-416, which classifies use-after-free conditions as a critical memory safety issue that can lead to arbitrary code execution or system instability.
From an operational impact perspective, this vulnerability enables remote attackers to either cause a denial of service by crashing the browser or potentially achieve more severe consequences including arbitrary code execution. The attack vector involves crafting malicious web content that triggers the specific sequence of DOM operations leading to the use-after-free condition. When successful, the vulnerability can result in browser crashes, rendering the application unusable for the victim, or in more sophisticated attacks where the attacker might leverage the memory corruption to execute malicious code with the privileges of the browser process. The vulnerability's impact extends beyond simple denial of service as it represents a potential path to full system compromise through memory corruption exploitation techniques.
The mitigation strategies for CVE-2015-6777 primarily involve updating to Google Chrome version 47.0.2526.73 or later, which contains the patched implementation of the ContainerNode::notifyNodeInsertedInternal function. Additionally, security researchers recommend implementing strict input validation for DOM operations and monitoring for unusual memory access patterns that might indicate similar vulnerabilities. Organizations should also consider deploying web application firewalls and content security policies to limit exposure to malicious content that might trigger such vulnerabilities. The fix implemented by Google addressed the memory management flow by ensuring proper reference counting and event handling for detached DOM nodes, aligning with ATT&CK technique T1059.007 for defensive measures against browser-based exploits. Network security teams should prioritize patching this vulnerability as part of their regular maintenance cycles, since the use-after-free condition creates a persistent risk that can be leveraged by threat actors without requiring user interaction beyond visiting compromised websites.