CVE-2021-21119 in Chrome
Summary
by MITRE • 02/09/2021
Use after free in Media in Google Chrome prior to 88.0.4324.96 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 • 02/26/2021
This vulnerability represents a critical use-after-free condition in the media handling components of Google Chrome browser versions prior to 88.0.4324.96. The flaw occurs within the browser's rendering engine where memory management fails to properly handle object lifecycles, creating opportunities for malicious code execution. The vulnerability specifically affects the media subsystem that processes multimedia content, making it particularly dangerous as it can be triggered through standard web page content. The issue arises when a renderer process is compromised and an attacker can manipulate memory objects that have already been freed, potentially leading to arbitrary code execution with the privileges of the compromised process. This type of vulnerability falls under CWE-416, which specifically addresses use-after-free errors in software implementations. The attack vector requires an attacker to first gain access to the renderer process through some initial compromise, then craft a malicious HTML page that triggers the specific memory management flaw during media processing operations. The operational impact extends beyond simple browser exploitation as it can enable attackers to escalate privileges and potentially gain full system control. According to ATT&CK framework, this vulnerability maps to technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the initial compromise typically involves gaining renderer process access followed by exploitation of memory corruption vulnerabilities. The heap corruption that results from this use-after-free condition can be leveraged to overwrite critical memory structures or execute malicious code in the context of the compromised browser process. The vulnerability demonstrates the inherent risks in complex multimedia processing components where memory management becomes particularly challenging due to the variety of media formats and processing paths involved. Security researchers have noted that such flaws often remain undetected for extended periods due to the complexity of memory management in modern browsers. The remediation strategy involves updating to Chrome version 88.0.4324.96 or later, which includes proper memory management fixes and additional safeguards against improper object deallocation. Organizations should also implement network-level protections such as content security policies and sandboxing mechanisms to limit the impact of potential exploitation attempts. Browser vendors typically address such issues through comprehensive memory safety improvements and enhanced runtime checks that prevent improper memory access patterns. The vulnerability underscores the importance of maintaining up-to-date browser software and implementing layered security approaches that protect against both initial compromise and subsequent exploitation phases. Additional mitigations include browser hardening configurations, restricted user privileges, and regular security assessments to identify and address similar memory corruption vulnerabilities in other browser components or third-party applications.