CVE-2020-6569 in Chrome
Summary
by MITRE
Integer overflow in WebUSB in Google Chrome prior to 85.0.4183.83 allowed a remote attacker who had compromised the renderer process to potentially exploit heap corruption via a crafted HTML page.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2020-6569 represents a critical integer overflow flaw within Google Chrome's WebUSB implementation that existed prior to version 85.0.4183.83. This issue resides in the browser's handling of USB device communication protocols and specifically affects the renderer process execution environment. The vulnerability classification aligns with CWE-190, which addresses integer overflow conditions that can lead to buffer overflows and memory corruption. WebUSB is a powerful browser API that enables websites to communicate directly with USB devices, creating a direct bridge between web applications and hardware peripherals. The implementation of this feature requires careful memory management and input validation to prevent malicious exploitation.
The technical flaw manifests when a malicious HTML page triggers an integer overflow condition during WebUSB device enumeration or data transfer operations. This overflow occurs in the memory allocation calculations used by the browser's USB handling code, potentially allowing an attacker to manipulate the size parameters used for heap memory allocation. When the renderer process is compromised through a separate attack vector, the attacker can leverage this vulnerability to corrupt heap memory structures and potentially execute arbitrary code with the privileges of the compromised renderer process. The vulnerability operates at the intersection of memory safety and browser security boundaries, where the renderer process has limited privileges but can still access system resources through the WebUSB API.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides a pathway for remote code execution within the browser environment. Attackers who have already gained access to the renderer process through other means can use this vulnerability to escalate their privileges and potentially gain deeper system access. The heap corruption that results from the integer overflow can lead to unpredictable behavior including crashes, data corruption, or more dangerous memory corruption that enables code execution. This vulnerability represents a significant concern for web application security as it demonstrates how seemingly benign browser APIs can become attack vectors when proper input validation and memory management are not implemented. The attack scenario typically requires a pre-existing compromise of the renderer process, making it a post-exploitation vulnerability that can be used to extend the attacker's capabilities within the browser environment.
Mitigation strategies for CVE-2020-6569 focus primarily on updating to Chrome version 85.0.4183.83 or later where the integer overflow has been patched. Organizations should implement comprehensive patch management protocols to ensure all browser installations remain current with security updates. The fix addresses the specific integer overflow condition in the WebUSB implementation by adding proper bounds checking and input validation for memory allocation calculations. Security teams should also consider implementing network-level protections such as web application firewalls and content filtering systems that can detect and block malicious HTML content. Additionally, browser hardening techniques including sandboxing and privilege separation should be maintained to limit the potential impact of any successful exploitation attempts. The vulnerability highlights the importance of continuous security monitoring and the need for robust input validation in all browser APIs, particularly those that provide direct hardware access capabilities. Organizations should also consider implementing security awareness training to help prevent initial compromise of renderer processes through phishing attacks or other social engineering techniques that could lead to exploitation of this vulnerability.