CVE-2017-6410 in KDE kio
Summary
by MITRE
kpac/script.cpp in KDE kio before 5.32 and kdelibs before 4.14.30 calls the PAC FindProxyForURL function with a full https URL (potentially including Basic Authentication credentials, a query string, or PATH_INFO), which allows remote attackers to obtain sensitive information via a crafted PAC file.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2017-6410 represents a significant information disclosure flaw within the KDE kio library and kdelibs components. This issue affects versions prior to 5.32 and 4.14.30 respectively, where the kio library fails to properly sanitize URL parameters when invoking the PAC (Proxy Auto-Configuration) FindProxyForURL function. The flaw stems from the improper handling of full HTTPS URLs that may contain Basic Authentication credentials, query strings, or PATH_INFO components during the proxy resolution process. This vulnerability falls under the CWE-200 category of Information Exposure and aligns with ATT&CK technique T1071.004 for application layer protocol manipulation.
The technical implementation of this vulnerability occurs when the kio library processes PAC files containing maliciously crafted proxy rules. When a PAC file is executed, the FindProxyForURL function receives a complete URL including authentication credentials, which are then passed through without adequate sanitization. This allows remote attackers to construct malicious PAC files that can extract sensitive information from the URL components. The vulnerability specifically targets the interaction between the PAC script execution environment and the URL parsing mechanism within the kio library, creating an information leakage channel that can be exploited by attackers positioned remotely. The flaw demonstrates a classic case of improper input validation and output sanitization in proxy configuration handling.
The operational impact of CVE-2017-6410 extends beyond simple information disclosure to potentially enable more sophisticated attacks. An attacker who can influence or control PAC files can extract authentication credentials embedded in URLs, including username and password components from Basic Authentication schemes. This capability allows for credential harvesting that could be used to gain unauthorized access to protected resources. The vulnerability also poses risks when URLs contain sensitive query parameters or path information that could reveal internal system details or user-specific data. Organizations relying on KDE-based applications for web browsing or proxy management face potential compromise of their network security posture, particularly in environments where PAC files are automatically downloaded or configured from untrusted sources.
Mitigation strategies for CVE-2017-6410 should focus on immediate version upgrades to patched releases of KDE kio and kdelibs components. System administrators must ensure all affected applications are updated to versions 5.32 or later for kio, and 4.14.30 or later for kdelibs. Additional protective measures include implementing strict access controls for PAC file distribution, validating and sanitizing all PAC file contents before deployment, and monitoring network traffic for suspicious PAC file requests. Organizations should also consider implementing network segmentation and proxy server hardening to reduce the attack surface. The remediation process must include comprehensive testing of updated components to ensure compatibility with existing proxy configurations while maintaining security controls. Security teams should monitor for potential exploitation attempts through network analysis and implement appropriate logging and alerting mechanisms to detect unauthorized PAC file modifications or access attempts.