CVE-2018-15515 in Central WiFiManager CWM-100
Summary
by MITRE
The CaptivelPortal service on D-Link Central WiFiManager CWM-100 1.03 r0098 devices will load a Trojan horse "quserex.dll" from the CaptivelPortal.exe subdirectory under the D-Link directory, which allows unprivileged local users to gain SYSTEM privileges.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability identified as CVE-2018-15515 represents a critical privilege escalation flaw within the D-Link Central WiFiManager CWM-100 device firmware version 1.03 r0098. This issue resides within the CaptivelPortal service component that manages wireless network access control and authentication processes. The vulnerability stems from improper privilege management and insecure loading mechanisms that allow local users to manipulate system components through carefully crafted file placement within the device's file system structure.
The technical exploitation mechanism involves the CaptivelPortal.exe executable loading a malicious dynamic link library file named "quserex.dll" from its own subdirectory within the D-Link installation directory. This loading behavior creates a path traversal and code injection vulnerability that bypasses normal security controls. The flaw operates under CWE-426 Untrusted Search Path, where the system loads components from predictable locations without proper validation of the source or integrity of the loaded modules. The vulnerability specifically targets the device's privilege escalation mechanisms, allowing unprivileged local accounts to achieve SYSTEM level privileges through manipulation of the service's dynamic loading behavior.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with complete system control over the affected device. Once local users gain SYSTEM privileges, they can modify network configurations, access sensitive data, install additional malware, or disable security features entirely. This vulnerability affects the device's core network management functionality and compromises the integrity of the entire wireless infrastructure it controls. The attack vector is particularly concerning because it requires minimal privileges to exploit, making it accessible to any user with local access to the device, whether through physical access, network-based attacks, or other initial compromise methods.
Security mitigations for this vulnerability should focus on immediate firmware updates from D-Link to address the flawed service loading mechanism and implement proper privilege separation. Network administrators should also consider disabling unnecessary services, implementing strict access controls, and monitoring for unauthorized file modifications in the D-Link directory structure. The vulnerability aligns with ATT&CK technique T1068 Privilege Escalation through the exploitation of insecure service loading mechanisms. Organizations should implement regular security assessments of network infrastructure devices and maintain up-to-date vulnerability management processes to prevent exploitation of similar path traversal and privilege escalation vulnerabilities. The incident highlights the importance of secure coding practices and proper privilege management in embedded systems, particularly those handling network access control functions.