CVE-2021-42101 in Apex One
Summary
by MITRE • 10/21/2021
An uncontrolled search path element vulnerabilities in Trend Micro Apex One and Apex One as a Service could allow a local attacker to escalate privileges on affected installations. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. This vulnerability is similar but not identical to CVE-2021-42103.
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Analysis
by VulDB Data Team • 10/28/2021
The vulnerability identified as CVE-2021-42101 represents a critical uncontrolled search path element issue affecting Trend Micro Apex One and Apex One as a Service products. This weakness falls under the broader category of path traversal and search path manipulation vulnerabilities that have long been recognized as significant security risks in enterprise security solutions. The vulnerability stems from how the affected software handles dynamic path resolution during component loading processes, creating opportunities for malicious actors to manipulate the execution flow through carefully crafted file paths that bypass normal security controls. The specific nature of this flaw allows for privilege escalation when combined with successful initial code execution, making it particularly dangerous in enterprise environments where security software typically operates with elevated privileges.
The technical implementation of this vulnerability exploits the improper handling of environmental variables and system path resolution within the Trend Micro Apex One framework. When the software attempts to locate and load required components, it processes search paths without adequate validation of the source or legitimacy of the referenced directories. This behavior creates an opportunity for local attackers who have already achieved low-privileged code execution to place malicious binaries in strategic locations within the search path. The vulnerability is classified under CWE-427 Uncontrolled Search Path Element, which specifically addresses situations where programs search for files using paths that contain untrusted input, particularly when those paths include directory names that can be manipulated by attackers. This weakness is particularly concerning because it operates at the core of application loading mechanisms, potentially allowing attackers to execute arbitrary code with the privileges of the targeted security software process.
The operational impact of CVE-2021-42101 extends beyond simple privilege escalation to potentially compromise entire enterprise security infrastructures. When successfully exploited, this vulnerability allows attackers to gain elevated system privileges that could enable them to bypass other security controls, access sensitive data, modify system configurations, or establish persistent backdoors within the organization's network. The attack vector requires initial compromise through low-privileged code execution, but this prerequisite is often achievable through various attack techniques including phishing, software exploitation, or social engineering. Organizations running affected Trend Micro Apex One installations face significant risk as the vulnerability can be leveraged to undermine the very security controls that protect against other threats, creating a dangerous scenario where the security solution itself becomes a potential attack vector. This makes the vulnerability particularly attractive to sophisticated threat actors who seek to maintain long-term access to enterprise networks.
Mitigation strategies for CVE-2021-42101 should focus on both immediate remediation and long-term architectural improvements to prevent similar issues. The primary recommendation involves applying the vendor-provided security patches and updates that address the specific search path handling mechanisms within Trend Micro Apex One. Organizations should also implement additional monitoring and access controls to detect unusual file placement activities in system directories that might indicate exploitation attempts. The vulnerability demonstrates the importance of implementing proper path validation and sanitization within security software, as well as following the principle of least privilege when configuring security applications. Security teams should also consider implementing runtime application self-protection measures and enhanced file integrity monitoring to detect potential exploitation attempts. From a defensive perspective, this vulnerability aligns with several ATT&CK tactics including privilege escalation and persistence, making it important for organizations to review their defensive strategies against these attack patterns. The incident underscores the critical need for security vendors to conduct thorough security testing of their software components, particularly those operating with elevated privileges, and for organizations to maintain comprehensive patch management processes that can quickly respond to such vulnerabilities.