CVE-2021-30575 in Chrome
Summary
by MITRE • 08/04/2021
Out of bounds write in Autofill in Google Chrome prior to 92.0.4515.107 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 • 08/07/2021
The vulnerability identified as CVE-2021-30575 represents a critical out-of-bounds write flaw within Google Chrome's Autofill component affecting versions prior to 92.0.4515.107. This issue resides in the browser's handling of user data input and form filling mechanisms, which are fundamental components of web browsing experiences. The vulnerability is particularly concerning because it can be exploited by attackers who have already compromised the renderer process, indicating a privilege escalation scenario where initial access has been achieved through other means. The out-of-bounds write condition occurs during the processing of crafted HTML content that triggers memory corruption within the Autofill subsystem.
The technical implementation of this vulnerability involves memory corruption through improper bounds checking in the Autofill functionality. When Chrome processes malicious HTML content containing crafted form elements or input fields, the Autofill component fails to properly validate array indices or buffer boundaries during data processing. This allows an attacker to write data beyond the allocated memory space, potentially overwriting adjacent memory locations. The flaw specifically manifests in the renderer process context, where Chrome's JavaScript engine executes untrusted web content, making it particularly dangerous as it can be triggered through standard web browsing activities. The vulnerability aligns with CWE-787 Out-of-bounds Write, which classifies improper bounds checking as a primary cause of memory corruption issues. The attack vector requires remote code execution within the renderer process, typically achieved through techniques such as cross-site scripting or supply chain compromises that allow initial code injection.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can enable attackers to achieve persistent access to user systems through heap-based exploitation techniques. When an attacker successfully exploits this vulnerability, they can manipulate the browser's memory layout to execute arbitrary code with the privileges of the compromised renderer process. This capability allows for further escalation to system-level access, particularly when combined with other exploitation techniques or when the renderer process has elevated privileges. The Autofill component's integration with user data handling makes this vulnerability particularly dangerous for users who frequently interact with web forms, as even benign-looking web pages could contain malicious code designed to trigger this specific memory corruption. The exploit can potentially lead to data theft, credential harvesting, or complete system compromise, making it a significant concern for enterprise environments where Chrome is widely deployed.
Mitigation strategies for CVE-2021-30575 primarily focus on immediate software updates to the latest Chrome versions that contain the necessary patches. Organizations should implement comprehensive patch management protocols to ensure all Chrome installations are updated promptly. Additional protective measures include implementing strict content security policies, deploying sandboxing mechanisms, and utilizing browser hardening techniques that limit the potential impact of such exploits. The vulnerability demonstrates the importance of maintaining current security patches and the risks associated with delayed updates, as it represents a known exploit that can be leveraged by threat actors without requiring sophisticated attack vectors. Network monitoring should also be enhanced to detect potential exploitation attempts through anomalous memory access patterns or unusual browser behavior. Security teams should also consider implementing web application firewalls and browser isolation solutions as additional protective layers against such memory corruption vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, highlighting the multi-stage nature of exploitation that can occur through such memory corruption flaws.