CVE-2021-30516 in Chrome
Summary
by MITRE • 06/04/2021
Heap buffer overflow in History in Google Chrome prior to 90.0.4430.212 allowed a remote attacker who had compromised the renderer process to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/10/2021
The heap buffer overflow vulnerability identified as CVE-2021-30516 represents a critical security flaw within Google Chrome's history management system that existed prior to version 90.0.4430.212. This vulnerability resides in the browser's handling of HTML content and specifically targets the memory allocation patterns used by the history component. The flaw manifests as a heap buffer overflow, which occurs when more data is written to a heap-allocated buffer than it can accommodate, leading to memory corruption that can be exploited by malicious actors. The vulnerability is particularly concerning because it requires only compromised renderer process access, meaning that an attacker who has already gained execution privileges within the browser's sandboxed environment can leverage this flaw to escalate their privileges and potentially achieve arbitrary code execution on the target system.
The technical implementation of this vulnerability involves improper bounds checking within Chrome's history processing code where HTML elements are parsed and stored in heap memory structures. When a crafted HTML page is processed by the browser, it triggers a specific code path that leads to buffer overflow conditions in the history component's memory management routines. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions where insufficient boundary checks allow data to overwrite adjacent memory locations. The attack vector requires an attacker to first compromise the renderer process through techniques such as cross-site scripting or other initial compromise methods, then leverage this specific heap overflow to gain additional control over the browser's memory space and potentially the underlying operating system.
The operational impact of CVE-2021-30516 extends beyond simple memory corruption as it provides a pathway for privilege escalation attacks that can be particularly devastating in targeted environments. Once an attacker exploits this vulnerability, they can potentially manipulate the browser's memory layout to execute arbitrary code with the privileges of the compromised renderer process, which typically runs with extensive access to user data and system resources. The vulnerability's exploitation potential aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the heap corruption can be leveraged to execute malicious payloads that bypass standard security controls. Organizations using affected Chrome versions face significant risk, as this vulnerability can be exploited remotely through web-based attacks, making it particularly dangerous for users who browse untrusted websites or encounter malicious advertisements that could trigger the exploitation chain.
Mitigation strategies for CVE-2021-30516 primarily focus on immediate remediation through browser updates to version 90.0.4430.212 or later, which contains the necessary patches to address the heap buffer overflow conditions. Security administrators should implement comprehensive patch management processes to ensure all user systems are updated promptly, as this vulnerability can be exploited without user interaction once a malicious webpage is loaded. Additional protective measures include implementing strict content security policies, enabling sandboxing features, and deploying web application firewalls that can detect and block malicious HTML content patterns associated with this exploit. The vulnerability also underscores the importance of maintaining up-to-date threat intelligence feeds and security monitoring systems that can detect anomalous behavior patterns indicating potential exploitation attempts. Organizations should conduct regular security assessments of their browser environments and implement browser hardening configurations that reduce the attack surface and limit the potential impact of such vulnerabilities.