CVE-2018-18344 in Chrome
Summary
by MITRE
Inappropriate allowance of the setDownloadBehavior devtools protocol feature in Extensions in Google Chrome prior to 71.0.3578.80 allowed a remote attacker with control of an installed extension to access files on the local file system via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 06/18/2023
The vulnerability identified as CVE-2018-18344 represents a critical security flaw in Google Chrome's handling of the devtools protocol within browser extensions. This issue specifically affected Chrome versions prior to 71.0.3578.80 and stems from an inappropriate allowance of the setDownloadBehavior feature within the devtools protocol for extensions. The flaw allows a remote attacker who has already gained the ability to install a malicious extension on a target system to execute arbitrary file system access operations. The vulnerability resides in the extension architecture where the devtools protocol is exposed to extensions without proper sandboxing or access controls, creating a dangerous privilege escalation vector. Attackers can leverage this capability to access sensitive files, potentially including user data, configuration files, and other system resources that should remain protected from extension-level access.
The technical implementation of this vulnerability involves the manipulation of Chrome's devtools protocol through a malicious extension that has already been installed on the target system. When an extension is granted access to the devtools protocol, it can utilize the setDownloadBehavior functionality to alter how Chrome handles file downloads, effectively bypassing normal file system access restrictions. This particular vulnerability is classified under CWE-284, which addresses improper access control, and represents a privilege escalation issue where a low-privilege extension gains elevated file system access capabilities. The flaw demonstrates a failure in the principle of least privilege within Chrome's extension security model, where extension developers should not have unrestricted access to file system operations that could compromise user privacy and system integrity.
From an operational perspective, this vulnerability creates a significant risk for users who install extensions from untrusted sources or when extensions are compromised through supply chain attacks. The attack vector requires an initial compromise of the extension installation process, which can occur through malicious extensions distributed through the Chrome Web Store or through phishing attacks that trick users into installing harmful extensions. Once installed, the malicious extension can leverage this vulnerability to access local files, potentially including browser cookies, saved passwords, personal documents, and other sensitive data stored on the user's system. This capability extends beyond simple file enumeration to include potential data exfiltration and further compromise of the user's digital environment, making it particularly dangerous for users who store sensitive information in their browsers or on their local systems.
The mitigation for CVE-2018-18344 requires immediate upgrading to Chrome version 71.0.3578.80 or later, which implements proper access controls for the devtools protocol within extensions. Organizations should also enforce strict extension installation policies, limiting extensions to those from trusted sources and implementing regular security audits of installed extensions. The vulnerability aligns with ATT&CK technique T1106, which covers execution through the Windows API, and demonstrates the importance of proper privilege separation in browser security models. Users should be educated about the risks of installing extensions from unverified sources and should regularly review their installed extensions for suspicious behavior. Additionally, security teams should monitor for any attempts to exploit this vulnerability through automated scanning tools and implement network-level detection measures to identify potential exploitation attempts. The fix implemented in Chrome 71.0.3578.80 demonstrates the importance of maintaining current software versions and the critical role of browser vendors in addressing security flaws that could compromise user privacy and system integrity through extension-based attack vectors.