CVE-2018-6176 in Chrome
Summary
by MITRE
Insufficient file type enforcement in Extensions API in Google Chrome prior to 68.0.3440.75 allowed a remote attacker who had compromised the renderer process to perform privilege escalation via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 07/18/2024
The vulnerability identified as CVE-2018-6176 represents a critical privilege escalation flaw within Google Chrome's Extensions API implementation. This weakness existed in Chrome versions prior to 68.0.3440.75 and specifically targeted the insufficient enforcement of file type validation mechanisms. The vulnerability arises from the browser's failure to properly validate file types when processing Chrome Extensions, creating a pathway for malicious actors to exploit compromised renderer processes and elevate their privileges within the system.
The technical flaw manifests in the Extensions API's inadequate validation of extension files, particularly those related to manifest.json and other extension components. When a renderer process is compromised through other attack vectors, an attacker can leverage this vulnerability to manipulate the extension loading process and gain elevated system privileges. The flaw essentially allows for a bypass of Chrome's security boundaries that normally separate the renderer process from the more privileged browser components. This type of vulnerability falls under CWE-20, which describes improper input validation, and more specifically aligns with CWE-787, representing out-of-bounds write conditions that can occur when input validation is insufficient.
The operational impact of CVE-2018-6176 is significant, as it enables remote attackers to escalate privileges from a compromised renderer process to system-level access. This escalation occurs without requiring additional user interaction or elevated privileges, making it particularly dangerous in environments where browser exploitation is possible. The vulnerability essentially provides an attacker who has already gained access to a renderer process with a means to break out of the sandboxed environment and gain broader system control. From an attack chain perspective, this vulnerability maps to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and represents a critical step in moving from initial compromise to persistent system access.
The mitigation strategy for this vulnerability requires immediate updating of Google Chrome to version 68.0.3440.75 or later, which includes proper file type validation enforcement in the Extensions API. Organizations should also implement additional security measures such as monitoring for unusual extension loading patterns and ensuring that Chrome extensions are only installed from trusted sources. Network administrators should consider implementing browser hardening policies that restrict extension installation and usage where possible. The fix implemented by Google addresses the core validation issue by strengthening the extension file type checking mechanisms within the browser's extension management system, thereby preventing unauthorized privilege escalation through malformed extension components. Security teams should also conduct regular audits of installed extensions and monitor for any suspicious activity that might indicate exploitation attempts.