CVE-2020-27697 in Security 2020
Summary
by MITRE • 11/19/2020
Trend Micro Security 2020 (Consumer) contains a vulnerability in the installer package that could be exploited by placing a malicious DLL in a non-protected location with high privileges (symlink attack) which can lead to obtaining administrative privileges during the installation of the product.
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Analysis
by VulDB Data Team • 12/08/2020
The vulnerability identified as CVE-2020-27697 resides within Trend Micro Security 2020 consumer edition installer package, representing a critical security flaw that exploits improper handling of dynamic link library files during the installation process. This vulnerability specifically targets the installer's failure to properly validate or secure the placement of dynamic libraries, creating an attack surface that malicious actors can leverage to escalate privileges. The flaw manifests when the installer processes DLL files from locations that lack proper access controls or privilege restrictions, allowing attackers to substitute legitimate libraries with malicious counterparts.
The technical implementation of this vulnerability follows a symbolic link attack pattern where an adversary places a crafted malicious DLL in a directory with elevated privileges that the installer will access during execution. This type of attack directly relates to CWE-59, which describes improper handling of a symbolic link, and CWE-276, which addresses incorrect permissions for privileged functions. The installer component fails to validate the integrity or authenticity of DLL files it encounters, particularly those in paths that may be manipulated by attackers with sufficient privileges to create or modify symbolic links.
Operationally, this vulnerability presents a significant risk to system security as it allows an attacker to execute arbitrary code with administrative privileges during the installation process. The attack requires the malicious actor to have access to a location where they can create symbolic links, typically a directory with write permissions, and the ability to influence the installation workflow. When the vulnerable installer runs, it will load the malicious DLL instead of the legitimate one, enabling the attacker to execute code with elevated privileges. This represents a privilege escalation vector that directly violates the principle of least privilege and can lead to complete system compromise.
The impact of this vulnerability extends beyond simple privilege escalation as it can enable attackers to install backdoors, modify system configurations, or establish persistent access to the compromised system. The attack chain typically involves creating a symbolic link pointing to a malicious DLL, ensuring the installer will load this malicious component, and then executing malicious code with administrative rights. This vulnerability aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" and specifically addresses the use of installer-based attacks. Organizations using Trend Micro Security 2020 consumer edition should immediately implement mitigations including restricting write permissions on installation directories, validating DLL integrity through code signing verification, and ensuring proper access controls on system directories where symbolic links could be created. Additionally, the vulnerability underscores the importance of secure installation practices and proper privilege management during software deployment operations.