CVE-2018-0517 in Net Security
Summary
by MITRE
Untrusted search path vulnerability in Anshin net security for Windows Version 16.0.1.44 and earlier allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 01/02/2020
The vulnerability identified as CVE-2018-0517 represents a critical untrusted search path weakness in Anshin net security software for Windows versions 16.0.1.44 and earlier. This flaw resides in the software's dynamic link library loading mechanism, where the application fails to properly validate or sanitize the search path used to locate required DLL files. The vulnerability stems from the software's insecure default behavior of searching for DLLs in user-writable directories without proper access controls or validation mechanisms, creating a privilege escalation vector that attackers can exploit through malicious DLL placement.
The technical implementation of this vulnerability aligns with CWE-427 Uncontrolled Search Path Element, where the application's search path includes directories that are not properly secured or validated. When the vulnerable software executes, it searches for required DLL components in a predetermined order that may include directories writable by unprivileged users. An attacker can place a malicious DLL with the same name as a legitimate component in one of these search paths, causing the system to load the attacker-controlled code instead of the intended legitimate DLL. This behavior constitutes a classic Trojan horse attack pattern where the malicious component masquerades as a legitimate system component.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially enable full system compromise. An attacker who successfully places a malicious DLL in the search path can execute arbitrary code with the privileges of the user running the vulnerable application, which may include administrative rights depending on how the security software is deployed. The vulnerability's exploitation requires minimal user interaction since it leverages the application's normal execution flow, making it particularly dangerous in enterprise environments where security software typically runs with elevated privileges. This weakness creates a persistent backdoor that can be maintained across system reboots and is difficult to detect through standard security monitoring.
Mitigation strategies for CVE-2018-0517 should focus on implementing proper DLL loading practices and reducing the attack surface available to potential attackers. Organizations should immediately upgrade to patched versions of Anshin net security software where available, as the vulnerability affects multiple versions of the product. System administrators should implement strict access controls on directories where security software components are installed, ensuring that only authorized users have write permissions. The principle of least privilege should be enforced by running security applications with minimal required permissions and by implementing application whitelisting solutions such as Windows Defender Application Control or similar technologies. Additionally, the use of secure coding practices including explicit DLL path specification and runtime checks for component integrity should be implemented to prevent similar vulnerabilities in custom applications. Network segmentation and monitoring solutions should be deployed to detect unusual DLL loading patterns that may indicate exploitation attempts. This vulnerability demonstrates the critical importance of secure coding practices and proper input validation in security software, as the very tools designed to protect systems can become entry points for attackers when not properly secured against common exploitation techniques. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically leveraging the technique of DLL side-loading to achieve unauthorized code execution with elevated privileges.