CVE-2018-10895 in qutebrowser
Summary
by MITRE
qutebrowser before version 1.4.1 is vulnerable to a cross-site request forgery flaw that allows websites to access 'qute://*' URLs. A malicious website could exploit this to load a 'qute://settings/set' URL, which then sets 'editor.command' to a bash script, resulting in arbitrary code execution.
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Analysis
by VulDB Data Team • 04/06/2023
The vulnerability identified as CVE-2018-10895 affects qutebrowser versions prior to 1.4.1 and represents a critical cross-site request forgery flaw that fundamentally undermines the browser's security model. This vulnerability stems from the browser's handling of qute:// protocol URLs, which are designed to provide privileged access to the browser's internal functionality and settings. The flaw allows malicious websites to exploit the browser's trust model by crafting requests that can access these privileged URLs without proper authentication or user consent, creating a dangerous attack vector that bypasses normal security boundaries.
The technical implementation of this vulnerability involves the exploitation of qutebrowser's internal protocol handler that manages qute:// URLs, which are typically restricted to the browser's own processes and user-initiated actions. When a malicious website loads a qute://settings/set URL through a crafted cross-site request forgery attack, it can manipulate the browser's configuration settings in ways that were never intended for external access. The specific exploitation targets the editor.command setting, which is a configuration parameter that determines what command the browser executes when launching an external editor. By setting this parameter to a bash script, the attacker can effectively inject arbitrary code execution capabilities into the browser's execution environment.
The operational impact of this vulnerability is severe and encompasses multiple layers of security compromise. An attacker who successfully exploits this flaw can achieve arbitrary code execution on the victim's system with the privileges of the browser process, potentially leading to full system compromise. This vulnerability directly violates the principle of least privilege and demonstrates a failure in the browser's input validation and access control mechanisms. The attack requires no user interaction beyond visiting a malicious website, making it particularly dangerous as it can be automated and deployed at scale. The vulnerability also represents a failure in the browser's security architecture, as it allows external websites to manipulate internal browser settings that should be restricted to authorized users or the browser's own processes.
The exploitation of this vulnerability aligns with several ATT&CK framework techniques including T1059 for executing malicious code and T1071 for application layer protocol usage. It also corresponds to CWE-352, which specifically addresses cross-site request forgery vulnerabilities, and CWE-284, which covers improper access control. The attack vector demonstrates how protocol handlers can be abused when proper validation is missing, particularly in browsers that implement custom protocols for internal functionality. The vulnerability represents a classic case of insufficient input sanitization where the browser fails to properly validate the origin of requests to privileged URLs, allowing external entities to manipulate internal browser state. Organizations using affected versions of qutebrowser should immediately update to version 1.4.1 or later, as this release includes proper access controls and validation mechanisms that prevent unauthorized access to qute:// URLs from external websites. The fix likely involves implementing proper origin validation and ensuring that only requests originating from within the browser's own processes can access privileged URLs, thereby closing the security gap that enabled this cross-site request forgery attack.