CVE-2020-6503 in Chrome
Summary
by MITRE
Inappropriate implementation in accessibility in Google Chrome prior to 74.0.3729.108 allowed a remote attacker to obtain potentially sensitive information from process memory via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/04/2020
The vulnerability identified as CVE-2020-6503 represents a critical security flaw in Google Chrome's accessibility implementation that existed prior to version 74.0.3729.108. This issue falls under the category of information disclosure vulnerabilities where an attacker can potentially extract sensitive data from process memory through malicious web content. The flaw specifically targets Chrome's accessibility features which are designed to assist users with disabilities by providing enhanced interaction capabilities with web content. These accessibility mechanisms include screen readers, keyboard navigation aids, and other assistive technologies that Chrome implements to ensure web accessibility compliance. The vulnerability arises from improper handling of accessibility data structures within the browser's memory management system, creating a pathway for unauthorized information extraction.
The technical implementation flaw stems from inadequate memory management practices within Chrome's accessibility subsystem where sensitive information remains accessible through crafted HTML pages. When Chrome processes web content with accessibility features enabled, it maintains certain data structures in memory that contain potentially sensitive information such as user interface element details, text content, or other process-specific data. The vulnerability occurs when malicious HTML pages trigger specific accessibility events that cause the browser to expose this memory content through improper data handling mechanisms. This type of vulnerability is classified as a memory disclosure issue and aligns with CWE-200, which addresses information exposure through improper error handling or data management. The flaw essentially allows attackers to bypass normal memory protection mechanisms that should prevent unauthorized access to process memory contents.
The operational impact of CVE-2020-6503 extends beyond simple information disclosure, as it provides attackers with a potential foothold for more sophisticated attacks within the browser environment. An attacker could leverage this vulnerability to gather sensitive user data, session information, or other process memory contents that might reveal patterns in user behavior or system configurations. The attack vector requires the victim to visit a malicious webpage, making this a client-side exploit that can be delivered through various means including phishing campaigns, compromised websites, or malicious advertisements. This vulnerability particularly affects users who rely on accessibility features, as the attack specifically targets the implementation of these features within the browser. The potential for exploitation increases when users have accessibility settings enabled, as the malicious page can trigger the specific code paths that expose the sensitive memory contents.
Mitigation strategies for CVE-2020-6503 primarily involve updating Chrome to version 74.0.3729.108 or later, which contains the necessary patches to address the accessibility implementation flaw. Organizations should implement comprehensive browser update policies to ensure all systems are running patched versions of Chrome and other affected browsers. Additionally, security teams should consider implementing network-level protections such as content filtering and web application firewalls to detect and block malicious content that might exploit this vulnerability. The ATT&CK framework categorizes this type of vulnerability under T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation, as attackers might use information obtained through memory disclosure to build more sophisticated attack chains. Browser vendors and security researchers recommend that users disable accessibility features when not actively needed, though this approach reduces functionality for users who require these features. Regular security assessments should include verification of browser versions and patch status to prevent exploitation of known vulnerabilities like CVE-2020-6503.