CVE-2021-1386 in Advanced Malware Protection
Summary
by MITRE • 04/08/2021
A vulnerability in the dynamic link library (DLL) loading mechanism in Cisco Advanced Malware Protection (AMP) for Endpoints Windows Connector, ClamAV for Windows, and Immunet could allow an authenticated, local attacker to perform a DLL hijacking attack on an affected Windows system. To exploit this vulnerability, the attacker would need valid credentials on the system. The vulnerability is due to insufficient validation of directory search paths at run time. An attacker could exploit this vulnerability by placing a malicious DLL file on an affected system. A successful exploit could allow the attacker to execute arbitrary code with SYSTEM privileges.
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Analysis
by VulDB Data Team • 04/11/2021
This vulnerability resides within the dynamic link library loading mechanisms of Cisco Advanced Malware Protection for Endpoints Windows Connector, ClamAV for Windows, and Immunet software components. The core technical flaw manifests as inadequate validation of directory search paths during runtime execution, creating a path traversal condition that enables malicious code execution through DLL hijacking techniques. The vulnerability specifically affects Windows operating systems where the affected software components are installed and running. According to CWE-426, this represents a classic insecure library loading vulnerability where the system fails to properly validate the source and authenticity of dynamically loaded libraries. The attack requires an authenticated local user with valid system credentials, which aligns with ATT&CK technique T1068 for local privilege escalation through legitimate system tools.
The operational impact of this vulnerability extends beyond simple code execution to achieve SYSTEM level privileges, representing a critical escalation path for attackers who have already gained initial access to the target system. When a malicious DLL is placed in a directory that is searched before the legitimate library locations, the system loads the attacker-controlled code instead of the intended library, allowing arbitrary code execution with elevated privileges. This creates a persistent threat vector that can be leveraged for privilege escalation, data exfiltration, or further lateral movement within the network. The vulnerability's exploitation potential is heightened because it operates at the Windows kernel level through legitimate system mechanisms, making detection more challenging for traditional security controls.
Mitigation strategies should focus on implementing proper DLL loading security practices including the use of absolute paths for library loading, enabling Windows Defender Application Control or similar application whitelisting solutions, and implementing strict directory permissions to prevent unauthorized DLL placement. Organizations should also conduct regular security audits to identify and remediate insecure library loading patterns within their software ecosystems. The principle of least privilege should be enforced by restricting local user permissions and implementing proper access controls for system directories. Additionally, network segmentation and monitoring solutions should be deployed to detect anomalous DLL loading behavior and unauthorized file placement activities. Regular patch management processes must be established to ensure timely deployment of vendor security updates and to maintain system integrity against known vulnerabilities.