CVE-2017-5021 in Chrome
Summary
by MITRE
A use after free in Google Chrome prior to 56.0.2924.76 for Linux, Windows and Mac, and 56.0.2924.87 for Android, 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 • 08/04/2020
The vulnerability identified as CVE-2017-5021 represents a critical use-after-free flaw in Google Chrome browsers across multiple platforms including Linux, Windows, Mac, and Android. This vulnerability stems from improper memory management within the browser's rendering engine, specifically affecting versions prior to Chrome 56.0.2924.76 for desktop platforms and 56.0.2924.87 for Android. The flaw manifests when the browser processes maliciously crafted HTML content, creating conditions where freed memory blocks are still accessed by subsequent operations.
The technical exploitation of this vulnerability involves a remote attacker who can craft a specific HTML page designed to trigger the use-after-free condition. When Chrome renders this malicious content, the browser's memory management system frees certain memory structures while simultaneously allowing code execution that attempts to access these already-released memory locations. This results in an out-of-bounds memory read operation that can be leveraged to extract sensitive information from the browser's memory space or potentially execute arbitrary code with the privileges of the browser process.
From an operational perspective, this vulnerability presents significant risks to users who browse the internet without proper security measures or up-to-date software. The remote nature of the attack means that users need only visit a compromised website or click on malicious links to be vulnerable. The out-of-bounds memory read can potentially expose sensitive data including cookies, session information, or other memory contents that may contain user credentials or private information. This vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of how improper memory management can lead to severe security implications in web browsers.
The attack vector for CVE-2017-5021 follows patterns consistent with the ATT&CK framework's technique T1059, where adversaries leverage browser-based attacks to execute malicious code. The vulnerability impacts the browser's sandboxing mechanisms and can potentially bypass security controls designed to isolate web content from the underlying operating system. Organizations and individuals should prioritize immediate patching of affected Chrome versions to prevent exploitation. The remediation involves updating to Chrome versions 56.0.2924.76 or later for desktop platforms and 56.0.2924.87 or later for Android devices, which include memory management fixes that prevent the use-after-free condition from occurring during HTML rendering operations.
Security researchers have documented similar patterns in other browser vulnerabilities where memory corruption issues lead to remote code execution capabilities, making this particular flaw particularly concerning for enterprise environments where users may be exposed to untrusted web content. The vulnerability demonstrates the importance of regular security updates and proper memory management practices in browser development, as even seemingly minor flaws in memory handling can result in significant security breaches that compromise user data and system integrity.