CVE-2025-49155: Trend Micro Apex One RCE Vulnerability

CVE-2025-49155 Overview

An uncontrolled search path vulnerability exists in the Trend Micro Apex One Data Loss Prevention (DLP) module that could allow an attacker to inject malicious code leading to arbitrary code execution on affected installations. This vulnerability (CWE-427) occurs when an application searches for external resources without properly validating the search path, allowing attackers to place malicious files in locations that will be loaded by the vulnerable application.

Critical Impact

Successful exploitation of this vulnerability allows attackers to achieve arbitrary code execution on systems running Trend Micro Apex One, potentially compromising endpoint security defenses and enabling further malicious activity within the network.

Affected Products

• Trend Micro Apex One (SaaS for Windows)
• Trend Micro Apex One (On-Premises for Windows)

Discovery Timeline

• 2025-06-17 - CVE-2025-49155 published to NVD
• 2025-09-09 - Last updated in NVD database

Technical Details for CVE-2025-49155

Vulnerability Analysis

This vulnerability affects the Data Loss Prevention module within Trend Micro Apex One, a widely deployed endpoint security solution. The uncontrolled search path flaw allows attackers to manipulate the order or location in which the application searches for dynamic libraries or executables. When the DLP module attempts to load a required component, it may inadvertently load a malicious file placed by an attacker in a directory that is searched before the legitimate location.

The attack requires user interaction, meaning a victim must perform some action that triggers the vulnerable code path—such as opening a specially crafted file or visiting a malicious location. Once triggered, the attacker-controlled code executes with the privileges of the Apex One process, which typically runs with elevated permissions to perform security monitoring functions.

Root Cause

The root cause is an uncontrolled search path element (CWE-427) in the DLP module's code. The application fails to properly specify absolute paths when loading external libraries or executables, instead relying on relative paths or system-defined search orders. This allows attackers to place malicious DLL files or executables in directories that are searched before the legitimate installation directory, resulting in the malicious code being loaded and executed.

Attack Vector

The vulnerability is exploitable via a network-based attack vector, though it requires user interaction to trigger. An attacker could craft a malicious payload and deliver it through various means such as email attachments, web downloads, or network shares. When a user interacts with the malicious content on a system running the vulnerable Apex One DLP module, the attack chain is initiated.

The attack typically follows this pattern: the attacker places a malicious DLL file with a specific name in a location accessible to the target system. When the DLP module loads and searches for its dependencies, it discovers the attacker's malicious file first due to the search path order vulnerability. The malicious code then executes with the same privileges as the Apex One process, potentially allowing complete system compromise.

Detection Methods for CVE-2025-49155

Indicators of Compromise

• Unexpected DLL files appearing in user-writable directories alongside Apex One installation paths
• Process execution anomalies where Apex One components spawn unexpected child processes
• Suspicious file write activity to directories in the system PATH or Apex One working directories
• Unusual network connections originating from Apex One DLP module processes

Detection Strategies

• Monitor for DLL loading events from non-standard directories by Apex One processes using endpoint detection tools
• Implement application whitelisting to detect and block unauthorized code execution from Apex One processes
• Deploy file integrity monitoring on Apex One installation directories and related system paths
• Use behavioral analysis to identify anomalous process trees involving Apex One components

Monitoring Recommendations

• Enable detailed logging for DLL load events on endpoints running Trend Micro Apex One
• Configure SIEM rules to alert on suspicious file creation in directories commonly used for DLL hijacking attacks
• Monitor for privilege escalation attempts following Apex One process activity
• Review Trend Micro agent logs for error messages that may indicate failed or successful exploitation attempts

How to Mitigate CVE-2025-49155

Immediate Actions Required

• Apply the security patch provided by Trend Micro as documented in their security advisory
• Review systems for indicators of compromise before and after patching
• Restrict write permissions to directories in the system search path and Apex One installation directories
• Consider temporarily disabling the DLP module on critical systems until patches can be applied

Patch Information

Trend Micro has released a security update to address this vulnerability. Administrators should consult the Trend Micro Solution Document for detailed patching instructions and download links. The Zero-Day Initiative Advisory ZDI-25-362 provides additional technical context regarding the vulnerability.

Organizations should prioritize patching based on the network-accessible nature of this vulnerability and its potential for arbitrary code execution.

Workarounds

• Implement strict directory permissions to prevent unauthorized users from writing files to locations in the DLL search path
• Use Windows Security features such as SafeDllSearchMode to modify DLL search order behavior
• Deploy application control solutions to prevent unauthorized code execution within Apex One process context
• Segment networks to limit exposure of systems running vulnerable Apex One installations until patches are applied