CVE-2020-6553 in Chrome
Summary
by MITRE
Use after free in offline mode in Google Chrome on iOS prior to 84.0.4147.125 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/05/2025
The vulnerability identified as CVE-2020-6553 represents a critical use-after-free condition affecting Google Chrome's offline mode implementation on iOS platforms. This flaw existed in Chrome versions prior to 84.0.4147.125 and enabled remote attackers to potentially exploit heap corruption through maliciously crafted HTML pages. The issue stems from improper memory management within the browser's offline capabilities, creating a scenario where freed memory locations could be accessed after their intended use, leading to unpredictable behavior and potential code execution.
The technical implementation of this vulnerability involves the browser's handling of memory resources during offline operations, where objects are deallocated from memory but references to these locations persist. When the offline mode component processes certain HTML elements or resources, it fails to properly invalidate pointers to freed memory blocks, allowing subsequent operations to access corrupted memory regions. This memory corruption can manifest in various ways including application crashes, data corruption, or more critically, arbitrary code execution. The flaw operates within the context of web rendering and offline storage mechanisms, making it particularly dangerous as it can be triggered through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious website.
From an operational impact perspective, this vulnerability presents significant security risks to iOS users who rely on Chrome for web browsing. Attackers could craft malicious web pages that, when loaded in Chrome's offline mode, would trigger the use-after-free condition and potentially execute arbitrary code on the target device. The remote exploitation capability means that users could be compromised simply by visiting a malicious website, making this vulnerability particularly concerning for enterprise environments where mobile security is paramount. The heap corruption aspect of this flaw could lead to complete system compromise, as memory corruption often provides attackers with opportunities to escalate privileges or gain deeper system access.
The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations, and demonstrates how improper memory management can create persistent security risks. From an attack framework perspective, this issue maps to multiple ATT&CK techniques including T1059 for command and control execution and T1070 for indicator removal. The remediation strategy for this vulnerability requires immediate patching of Chrome to version 84.0.4147.125 or later, which implements proper memory deallocation and pointer invalidation mechanisms. Organizations should also consider implementing network-level controls to block access to known malicious domains and maintain comprehensive monitoring of browser-based threats. Additionally, user education regarding the dangers of visiting untrusted websites and the importance of keeping software updated remains crucial in mitigating the risk associated with this and similar vulnerabilities.