CVE-2017-11657 in Dashlane
Summary
by MITRE
Dashlane might allow local users to gain privileges by placing a Trojan horse WINHTTP.dll in the %APPDATA%\Dashlane directory.
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Analysis
by VulDB Data Team • 11/03/2019
The vulnerability identified as CVE-2017-11657 represents a local privilege escalation issue within the Dashlane password manager application that stems from insecure library loading practices. This flaw allows attackers to elevate their system privileges by manipulating the application's dynamic link library loading mechanism, specifically targeting the WINHTTP.dll component that Dashlane relies upon for network communications. The vulnerability exists because the application does not properly validate or secure the loading of dynamic libraries from user-accessible directories, creating an attack surface where malicious actors can place crafted malicious libraries that will be executed with elevated privileges.
The technical exploitation of this vulnerability occurs through a classic Trojan horse attack vector where an attacker places a malicious WINHTTP.dll file within the %APPDATA%\Dashlane directory. This directory is typically writable by regular users and is used by Dashlane for application data storage. When Dashlane executes and attempts to load the WINHTTP.dll library for network operations, the system loads the attacker-controlled malicious version instead of the legitimate system library. This behavior violates the principle of least privilege and demonstrates a failure in proper library resolution and validation mechanisms. The vulnerability directly maps to CWE-427 Uncontrolled Search Path Element, which describes how applications that search for libraries or files in insecure paths can be exploited by attackers who place malicious files in those locations.
The operational impact of this vulnerability is significant as it provides local attackers with the ability to escalate their privileges to the system level when Dashlane is running with elevated permissions. This privilege escalation capability allows attackers to execute arbitrary code with the highest system privileges, potentially leading to complete system compromise. The vulnerability is particularly concerning because it requires no special permissions to exploit initially, as the %APPDATA% directory is accessible to regular users. Once exploited, the attacker can modify system files, install additional malware, access sensitive data, and maintain persistence within the compromised system. This type of vulnerability aligns with ATT&CK technique T1068, which covers Local Privilege Escalation, and specifically addresses the use of DLL hijacking or library loading vulnerabilities for privilege escalation.
Mitigation strategies for CVE-2017-11657 should focus on both immediate application-level fixes and broader system security improvements. Application vendors should implement proper library loading mechanisms that explicitly specify full paths to system libraries or use secure library loading practices that prevent loading of unauthorized libraries from user-accessible directories. System administrators should consider implementing file system permissions that restrict write access to application data directories, particularly those used for dynamic library loading. The use of application whitelisting solutions like Windows AppLocker can help prevent unauthorized DLL execution. Additionally, regular security audits should verify that applications do not rely on insecure library search paths, and that dynamic library loading follows secure coding practices. Organizations should also implement monitoring for suspicious file creation in application data directories and ensure that all software updates are applied promptly to address known vulnerabilities. The vulnerability highlights the importance of following secure coding guidelines and implementing defense-in-depth strategies to prevent similar issues from occurring in other applications.