CVE-2018-6136 in Chrome
Summary
by MITRE
Missing type check in V8 in Google Chrome prior to 67.0.3396.62 allowed a remote attacker to perform an out of bounds memory read via a crafted HTML page.
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Analysis
by VulDB Data Team • 07/18/2024
The vulnerability identified as CVE-2018-6136 represents a critical security flaw in the V8 JavaScript engine used within Google Chrome browsers prior to version 67.0.3396.62. This issue stems from a missing type check that fundamentally compromises the memory safety mechanisms inherent to the JavaScript engine. The vulnerability specifically affects the engine's handling of object types during memory operations, creating a scenario where malicious code can manipulate type information in ways that bypass normal safety protocols. The flaw resides in the V8 engine's internal type system which is responsible for ensuring that memory operations occur within valid boundaries and that objects maintain their expected types throughout execution.
The technical implementation of this vulnerability allows remote attackers to construct malicious HTML pages that trigger an out of bounds memory read condition. This occurs when the V8 engine fails to properly validate type information before performing memory operations, enabling attackers to read data from memory locations that should remain protected. The missing type check creates a pathway where crafted JavaScript code can manipulate object type descriptors in such a way that subsequent memory accesses reference invalid memory addresses. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, though specifically manifests within the context of type system validation within JavaScript engines. The vulnerability can be exploited through standard web browsing scenarios where users visit compromised websites, making it particularly dangerous in real-world environments.
The operational impact of CVE-2018-6136 extends beyond simple information disclosure, as out of bounds memory reads can potentially expose sensitive data from memory segments including browser internals, user credentials, or other confidential information. Attackers can leverage this vulnerability to gather information that might aid in subsequent exploitation attempts, including heap layout information or other memory contents that could be used to bypass security mitigations such as address space layout randomization. The remote nature of this exploit means that users need only visit a malicious website to be compromised, eliminating the need for complex social engineering or physical access. This vulnerability aligns with ATT&CK technique T1059.007 for JavaScript and with T1071.001 for application layer protocol usage, as it leverages web browser execution contexts and JavaScript engine capabilities to achieve its objectives.
Mitigation strategies for this vulnerability require immediate browser updates to version 67.0.3396.62 or later, which includes patches that restore proper type checking mechanisms within the V8 engine. Organizations should implement comprehensive patch management processes to ensure all affected systems receive updates promptly, as this vulnerability can be exploited without user interaction. Additional protective measures include implementing web application firewalls that can detect and block malicious JavaScript patterns, enabling sandboxing mechanisms where available, and utilizing browser security features such as content security policies. The vulnerability demonstrates the critical importance of type safety in JIT compilation environments and highlights the need for robust validation mechanisms in complex software systems. Security teams should monitor for indicators of compromise related to this vulnerability and implement network-based detection measures to identify potential exploitation attempts.