CVE-2018-6124 in Chrome
Summary
by MITRE
Type confusion in ReadableStreams in Blink in Google Chrome prior to 67.0.3396.62 allowed a remote attacker to potentially exploit object corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/23/2023
The vulnerability identified as CVE-2018-6124 represents a critical type confusion flaw within the Blink rendering engine of Google Chrome browsers. This issue specifically affects the ReadableStreams implementation and existed in versions prior to 67.0.3396.62, making it a significant security concern for users running affected browser versions. The vulnerability stems from improper handling of object types during stream processing operations, creating conditions where malicious code could manipulate object memory structures. The flaw manifests when the browser processes crafted HTML content that triggers unexpected behavior in the stream handling mechanisms, potentially leading to memory corruption scenarios.
The technical implementation of this vulnerability involves a type confusion attack vector where the browser's JavaScript engine fails to properly validate object types during ReadableStream operations. When processing maliciously crafted HTML pages, the engine may incorrectly interpret memory locations or object references, leading to situations where one data type is treated as another. This type confusion allows attackers to manipulate object layout in memory, potentially enabling arbitrary code execution. The vulnerability specifically targets the interaction between JavaScript and the underlying C++ implementation of stream processing, where type checking mechanisms fail to prevent cross-type memory access patterns. According to CWE classification, this represents a CWE-476: NULL Pointer Dereference combined with CWE-121: Stack-based Buffer Overflow, as the type confusion can lead to memory corruption that may result in buffer overflows or pointer manipulation attacks.
The operational impact of CVE-2018-6124 extends beyond simple browser exploitation, as it provides attackers with a remote code execution capability through web-based attacks. An attacker could craft a malicious webpage that, when loaded in a vulnerable Chrome browser, would trigger the type confusion during stream processing operations. This could lead to complete system compromise, as the attacker would gain the ability to execute arbitrary code with the privileges of the browser process. The vulnerability is particularly concerning because it requires no user interaction beyond visiting a malicious website, making it suitable for drive-by download attacks. The attack surface is broad since ReadableStreams are commonly used in web applications, particularly in scenarios involving file processing, network communication, or data streaming operations. This vulnerability aligns with ATT&CK technique T1059.007: Command and Scripting Interpreter: JavaScript, as it exploits JavaScript execution contexts to manipulate browser internals.
Mitigation strategies for CVE-2018-6124 primarily focus on immediate browser updates to versions 67.0.3396.62 or later where the vulnerability has been patched. Organizations should implement comprehensive browser update policies and consider using automated update mechanisms to ensure rapid deployment of security patches. Additionally, network administrators can deploy web application firewalls or content filtering solutions to block access to known malicious domains that may host exploit code. Browser security configurations should be hardened by disabling unnecessary JavaScript features and implementing strict content security policies. The patch addresses the root cause by strengthening type validation checks within the ReadableStream implementation, ensuring proper object type handling during stream operations. Security teams should monitor for exploitation attempts through network traffic analysis and implement intrusion detection systems to identify potential exploitation attempts. Regular security assessments of web applications that utilize stream processing should be conducted to identify potential attack vectors that could leverage similar vulnerabilities. The vulnerability demonstrates the importance of maintaining up-to-date browser software and implementing defense-in-depth strategies to protect against zero-day exploits that target browser engine internals.