CVE-2023-5487 in Chrome
Summary
by MITRE • 10/25/2023
Inappropriate implementation in Fullscreen in Google Chrome prior to 118.0.5993.70 allowed an attacker who convinced a user to install a malicious extension to bypass navigation restrictions via a crafted Chrome Extension. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 10/29/2023
The vulnerability identified as CVE-2023-5487 represents a critical flaw in Google Chrome's fullscreen implementation that undermines the browser's security model for extension management. This issue specifically affects Chrome versions prior to 118.0.5993.70 and stems from an inappropriate implementation that fails to properly validate navigation restrictions when malicious extensions are installed. The vulnerability operates through a sophisticated attack vector where an adversary must first convince a user to install a crafted malicious extension, which then leverages the flawed fullscreen functionality to bypass established security boundaries.
The technical flaw manifests in the improper handling of fullscreen mode permissions within Chrome's extension architecture. When a user installs a malicious extension, the vulnerability allows the extension to manipulate fullscreen contexts in ways that circumvent the normal navigation restrictions that should be enforced by the browser's security model. This bypass occurs specifically during fullscreen transitions where the extension can exploit a gap in the permission validation process, enabling it to navigate to arbitrary URLs or execute malicious code without proper user consent or security checks. The issue falls under the CWE-693 weakness category, which deals with protection mechanism failures, particularly in the context of access control mechanisms.
The operational impact of this vulnerability extends beyond simple navigation bypass, creating potential pathways for more severe attacks including phishing, credential theft, and data exfiltration. Attackers can leverage this vulnerability to create convincing fake browser interfaces that appear legitimate while actually redirecting users to malicious sites or extracting sensitive information. The medium severity classification by Chromium security team reflects the fact that while user interaction is required for initial compromise, the post-exploitation capabilities can be quite dangerous. This vulnerability directly relates to the ATT&CK technique T1170 - "Path Interception" and T1059 - "Command and Scripting Interpreter" as it enables attackers to manipulate browser navigation and execute malicious code through the compromised extension.
Mitigation strategies for CVE-2023-5487 primarily focus on immediate browser updates to versions 118.0.5993.70 and later where the vulnerability has been patched. Organizations should implement comprehensive extension management policies that restrict installation of third-party extensions and conduct regular audits of installed extensions. Security teams should also deploy network monitoring solutions to detect suspicious navigation patterns that might indicate exploitation attempts. The patch addresses the core implementation flaw by strengthening permission validation during fullscreen transitions and ensuring that extension navigation restrictions remain intact regardless of the browser's display mode. Additionally, user education programs should emphasize the risks of installing extensions from untrusted sources, as this remains the primary attack vector for exploiting the vulnerability.