CVE-2021-36744 in Security
Summary
by MITRE • 09/06/2021
Trend Micro Security (Consumer) 2021 and 2020 are vulnerable to a directory junction vulnerability which could allow an attacker to exploit the system to escalate privileges and create a denial of service.
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Analysis
by VulDB Data Team • 09/09/2021
The vulnerability identified as CVE-2021-36744 affects Trend Micro Security Consumer versions 2020 and 2021, representing a critical directory junction flaw that exposes systems to privilege escalation attacks. This vulnerability stems from improper handling of directory junctions within the security software's file system operations, creating a pathway for malicious actors to manipulate the system's security mechanisms. The flaw specifically impacts how the software processes symbolic links and directory junctions, allowing attackers to bypass security controls through crafted file system operations that exploit the underlying trust model of the application.
Directory junctions are file system constructs that provide a way to redirect file system requests from one location to another, serving as a legitimate administrative tool for system administrators. However, when improperly implemented, these junctions can become attack vectors for privilege escalation. The vulnerability manifests when Trend Micro Security fails to properly validate or sanitize directory junction paths, allowing an attacker to create malicious junctions that point to system-critical files or directories. This weakness aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-78, which addresses OS command injection through improper input validation. The attack surface is particularly concerning as it allows adversaries to manipulate the security software itself rather than targeting the underlying operating system directly.
The operational impact of this vulnerability extends beyond simple privilege escalation to include potential denial of service conditions that can severely compromise system availability. An attacker who successfully exploits this vulnerability can not only elevate their privileges to system level but also manipulate the security software's operational behavior, potentially disabling security features or redirecting system resources. This dual impact makes the vulnerability particularly dangerous in enterprise environments where Trend Micro Security is deployed as a primary defense mechanism. The exploitability of this flaw increases significantly when attackers can influence the system's file creation process or when the software runs with elevated privileges, creating scenarios where malicious junctions can be established during normal system operations. The vulnerability can be leveraged to create persistent access points that survive system restarts and can be used to maintain control over compromised systems.
Mitigation strategies for CVE-2021-36744 should focus on immediate software updates from Trend Micro, as the vendor has released patches addressing this specific vulnerability. Organizations should implement network segmentation to limit the potential impact of exploitation and monitor for suspicious file system activities that might indicate junction creation attempts. Security teams should also consider implementing additional access controls and privilege management policies to reduce the attack surface available to potential exploiters. The remediation process should include thorough system audits to identify any malicious junctions that may have been established prior to patching, as well as monitoring for indicators of compromise such as unexpected privilege escalation events or unusual file system operations. Additionally, system administrators should review and harden the configuration of Trend Micro Security to limit its ability to create or modify directory junctions, aligning with the principle of least privilege and reducing the potential impact of such vulnerabilities in future scenarios. This vulnerability demonstrates the importance of secure file system handling practices and proper input validation in security software, as highlighted by ATT&CK technique T1059.001 for command and scripting interpreter usage and T1068 for exploit for privilege escalation.