CVE-2018-6118 in Chrome
Summary
by MITRE
A double-eviction in the Incognito mode cache that lead to a user-after-free in cache in Google Chrome prior to 66.0.3359.139 allowed a remote attacker who had compromised the renderer process to execute arbitrary code via a crafted HTML page.
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Analysis
by VulDB Data Team • 07/18/2024
The vulnerability identified as CVE-2018-6118 represents a critical memory safety issue within Google Chrome's Incognito mode cache implementation that existed prior to version 66.0.3359.139. This flaw manifests as a double-eviction condition within the cache management system, creating a scenario where memory locations are freed twice, leading to a user-after-free condition that can be exploited for arbitrary code execution. The vulnerability specifically impacts Chrome's rendering process and requires an attacker who has already compromised this process to leverage the flaw effectively.
The technical root cause of this vulnerability stems from improper memory management within Chrome's cache subsystem when operating in Incognito mode. During the eviction process, the system attempts to remove entries from the cache multiple times, causing memory deallocation to occur twice on the same memory segment. This double-free condition creates a dangling pointer that can be manipulated by an attacker to control the execution flow of the application. The issue is categorized under CWE-415 as an double free vulnerability, which is a well-known class of memory safety flaws that can lead to privilege escalation and arbitrary code execution.
When exploited, this vulnerability allows a remote attacker who has already gained access to the renderer process to execute arbitrary code with the privileges of the Chrome process. The attack vector requires a specially crafted HTML page that triggers the specific cache eviction sequence leading to the double-free condition. The operational impact is significant as it represents a privilege escalation vulnerability that can be leveraged to bypass security boundaries within the browser environment. This flaw essentially provides an attacker with a path to execute malicious code within the context of the Chrome application, potentially leading to complete system compromise if combined with other exploitation techniques.
The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the exploitation would involve executing code through the browser's JavaScript engine. It also relates to T1068 for exploit for privilege escalation, since the double-free condition allows for privilege escalation within the browser's security model. Organizations should prioritize immediate patching of Chrome installations to version 66.0.3359.139 or later, as this vulnerability was specifically addressed through memory management improvements in the cache subsystem. Additional mitigations include implementing strict browser sandboxing policies and monitoring for unusual memory access patterns that could indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in browser security and highlights the need for continuous security auditing of complex caching mechanisms in web browsers.