CVE-2018-6138 in Chrome
Summary
by MITRE
Insufficient policy enforcement in Extensions API in Google Chrome prior to 67.0.3396.62 allowed an attacker who convinced a user to install a malicious extension to bypass navigation restrictions via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 07/18/2024
The vulnerability identified as CVE-2018-6138 represents a critical weakness in Google Chrome's Extensions API that undermined the browser's security model for extension management and navigation control. This flaw existed in Chrome versions prior to 67.0.3396.62 and created a significant attack vector that could be exploited by malicious actors seeking to circumvent user-defined security restrictions. The vulnerability specifically targeted the insufficient enforcement of policies within the extensions framework, allowing attackers to manipulate how navigation restrictions were applied to extension-based applications.
The technical implementation of this vulnerability stemmed from inadequate validation and enforcement mechanisms within Chrome's extension management system. When users installed extensions, the browser failed to properly verify or enforce the navigation restrictions that should have been applied to those extensions. This weakness enabled attackers to craft specially designed extensions that could bypass the normal security boundaries imposed by the browser's policy enforcement system. The flaw essentially allowed malicious extensions to operate outside the intended scope of permissions and restrictions that users or administrators had set.
From an operational perspective, this vulnerability created a serious risk for users who might have installed extensions under the assumption that navigation restrictions were properly enforced. Attackers could exploit this weakness by developing extensions that appeared legitimate but contained malicious navigation capabilities. The attack required social engineering to convince users to install the malicious extension, but once installed, the extension could bypass restrictions that should have prevented access to certain websites or navigation patterns. This created a persistent threat vector that could be used for data exfiltration, phishing attacks, or other malicious activities.
The implications of this vulnerability extend beyond simple navigation bypassing and represent a broader failure in Chrome's permission model and policy enforcement. This weakness aligns with CWE-693, which deals with protection mechanism failures, and could be categorized under ATT&CK technique T1176 for bypassing user execution restrictions. Organizations relying on Chrome-based environments faced potential exposure to targeted attacks that could exploit this vulnerability to circumvent security controls that were meant to protect against malicious navigation patterns and access restrictions. The vulnerability highlighted the critical importance of proper policy enforcement in browser extension systems and demonstrated how seemingly minor implementation flaws could create significant security risks.
Effective mitigation strategies for this vulnerability required immediate browser updates to version 67.0.3396.62 or later, which contained the necessary fixes to properly enforce extension policies. Additionally, users should have been advised to review their installed extensions and remove any that were suspicious or unnecessary. Organizations needed to implement proactive monitoring of extension installations and ensure that their security policies properly accounted for the potential risks associated with extension-based navigation bypasses. The fix implemented by Google addressed the core policy enforcement mechanisms, restoring proper validation of navigation restrictions and ensuring that extensions could not bypass the security controls that users had established.