CVE-2018-6086 in Chrome
Summary
by MITRE
A double-eviction in the Incognito mode cache that lead to a user-after-free in Networking Disk Cache in Google Chrome prior to 66.0.3359.106 allowed a remote attacker to execute arbitrary code via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability identified as CVE-2018-6086 represents a critical memory corruption issue within Google Chrome's networking disk cache implementation specifically affecting Incognito mode operations. This double-eviction condition occurs when the cache system attempts to remove and reinitialize cache entries simultaneously, creating a scenario where memory locations are freed twice before being properly reallocated. The flaw exists in the underlying cache management system that handles temporary network resources during browsing sessions, particularly when users engage in private browsing activities. The vulnerability demonstrates a classic user-after-free condition that arises from improper memory management practices within the browser's networking subsystem.
The technical exploitation of this vulnerability leverages the specific timing and sequence of cache eviction operations that occur in Incognito mode. When multiple cache entries are processed for removal simultaneously, the system fails to properly track memory references, leading to a situation where freed memory blocks are accessed after being deallocated. This memory corruption creates a potential code execution vector that allows remote attackers to inject and execute arbitrary code on affected systems. The attack requires a malicious HTML page that can trigger the specific cache eviction sequence, typically involving crafted network requests that force the browser to process multiple cache entries concurrently. This vulnerability directly maps to CWE-415, which describes improper double-free conditions in memory management, and represents a significant escalation from the more common heap-based memory corruption issues.
The operational impact of this vulnerability extends beyond simple code execution capabilities to encompass potential full system compromise when exploited successfully. Remote attackers can leverage this flaw to bypass security restrictions and execute malicious payloads with the privileges of the Chrome process. The vulnerability affects all versions of Chrome prior to 66.0.3359.106, making it particularly dangerous as it impacts a substantial user base. The Incognito mode context adds additional risk since users often trust private browsing sessions to provide enhanced security, making them more likely to visit malicious sites without suspicion. This vulnerability aligns with ATT&CK technique T1059.007, which covers the execution of malicious code through web browsers, and represents a sophisticated attack vector that requires precise timing and memory manipulation to achieve successful exploitation.
Mitigation strategies for CVE-2018-6086 primarily focus on immediate patch deployment and browser version updates to ensure users operate on patched versions of Chrome. Organizations should implement comprehensive patch management protocols to rapidly deploy the Chrome 66.0.3359.106 update or later versions that contain the necessary memory management fixes. Browser hardening measures including sandboxing enhancements and strict content security policies can provide additional defense layers. Network monitoring solutions should be configured to detect suspicious web traffic patterns that might indicate exploitation attempts. The vulnerability also underscores the importance of regular security audits of browser components and cache management systems. Security teams should implement proactive monitoring for similar memory corruption patterns and consider implementing automated vulnerability scanning tools that can detect potential double-free conditions in browser implementations. Organizations should also maintain awareness of related vulnerabilities in the Chrome codebase and ensure comprehensive testing of browser updates before deployment to prevent similar issues from emerging in their environments.