CVE-2020-6504 in Chrome
Summary
by MITRE
Insufficient policy enforcement in notifications in Google Chrome prior to 74.0.3729.108 allowed a remote attacker to bypass notification restrictions via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/04/2020
The vulnerability identified as CVE-2020-6504 represents a critical weakness in Google Chrome's notification policy enforcement mechanism that existed prior to version 74.0.3729.108. This flaw falls under the category of insufficient policy enforcement, a common security pattern that allows attackers to circumvent intended access controls and system limitations. The issue specifically affects how Chrome handles notification permissions and restrictions, creating a pathway for malicious actors to bypass established security boundaries that should prevent unauthorized notification delivery to users.
The technical implementation of this vulnerability stems from inadequate validation of notification requests within Chrome's security model. When a web page attempts to display notifications, Chrome typically enforces strict permission policies that require explicit user consent before allowing notification delivery. However, the flaw in the affected versions allowed a crafted HTML page to manipulate the notification system in ways that circumvented these established permission checks. This manipulation could occur through subtle exploitation of how Chrome processes notification requests, potentially leveraging race conditions or improper state validation within the browser's notification handling subsystem.
The operational impact of this vulnerability extends beyond simple notification bypass, as it represents a broader failure in Chrome's permission model that could enable more sophisticated attacks. Attackers could potentially use this vulnerability to deliver malicious notifications that appear legitimate to users, potentially leading to social engineering campaigns or phishing attempts that exploit the user's trust in the browser's notification system. The implications are particularly concerning given that notifications are often perceived as trusted elements of web applications, making users more likely to interact with malicious content that appears to come from legitimate sources.
This vulnerability aligns with CWE-693, which describes protection mechanism failures where security controls fail to properly protect against attacks. The flaw demonstrates how insufficient policy enforcement can create attack vectors that bypass fundamental security assumptions built into the browser's architecture. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, as it allows attackers to bypass user consent mechanisms that would normally protect against unwanted notification delivery. The attack surface is particularly concerning in enterprise environments where notification-based attacks could be used to bypass security awareness training or to deliver malicious payloads through notification click-throughs.
The mitigation strategy for this vulnerability required immediate browser updates to patch the notification policy enforcement mechanism. Google's release of Chrome version 74.0.3729.108 included comprehensive fixes that restored proper validation of notification requests and ensured that permission policies were consistently enforced. Organizations should prioritize updating to patched versions and consider implementing additional monitoring for suspicious notification-related activities. Security teams should also review existing notification-based security policies and user training programs to address potential exploitation vectors that might have been enabled by this vulnerability. The incident underscores the importance of maintaining up-to-date browser security implementations and demonstrates how seemingly minor policy enforcement flaws can create significant security risks in user-facing applications.