CVE-2025-49217: Trend Micro Endpoint Encryption RCE Flaw

CVE-2025-49217 Overview

An insecure deserialization vulnerability exists in the Trend Micro Endpoint Encryption PolicyServer that enables pre-authentication remote code execution on affected installations. This vulnerability is similar to CVE-2025-49213 but affects a different method within the PolicyServer component. The flaw allows unauthenticated remote attackers to execute arbitrary code with elevated privileges on vulnerable systems, potentially leading to complete system compromise.

Critical Impact

This pre-authentication remote code execution vulnerability allows attackers to execute arbitrary code without any credentials, enabling complete system takeover of Trend Micro Endpoint Encryption PolicyServer installations.

Affected Products

• Trend Micro Endpoint Encryption PolicyServer
• Microsoft Windows (as the underlying operating system)

Discovery Timeline

• June 17, 2025 - CVE-2025-49217 published to NVD
• September 8, 2025 - Last updated in NVD database

Technical Details for CVE-2025-49217

Vulnerability Analysis

This vulnerability stems from two related weaknesses identified as CWE-477 (Use of Obsolete Function) and CWE-502 (Deserialization of Untrusted Data). The Trend Micro Endpoint Encryption PolicyServer processes serialized data from network requests without proper validation, allowing attackers to craft malicious payloads that execute arbitrary code upon deserialization.

The pre-authentication nature of this vulnerability is particularly concerning as it requires no user interaction or valid credentials to exploit. An attacker with network access to the PolicyServer can send specially crafted serialized objects that, when processed by the vulnerable deserialization method, result in arbitrary code execution with the privileges of the PolicyServer service.

Root Cause

The root cause of this vulnerability lies in the use of obsolete deserialization functions (CWE-477) combined with improper handling of untrusted serialized data (CWE-502). The affected method in the PolicyServer fails to validate or sanitize incoming serialized objects before deserializing them, allowing attackers to inject malicious object chains that execute code during the deserialization process.

This is a variant of CVE-2025-49213, affecting a different deserialization method within the same codebase, suggesting systemic issues with how serialized data is handled throughout the PolicyServer application.

Attack Vector

The attack vector is network-based, requiring no authentication and no user interaction. An attacker can exploit this vulnerability remotely by sending specially crafted HTTP requests containing malicious serialized payloads to the PolicyServer endpoint. The vulnerability affects confidentiality, integrity, and availability of the target system, as successful exploitation grants the attacker full control over the compromised server.

Exploitation typically involves crafting a serialized object payload that leverages available gadget chains in the application's classpath. When the vulnerable method deserializes the malicious payload, it triggers a chain of method calls that ultimately execute attacker-controlled code. For detailed technical information, refer to the Zero Day Initiative Advisory ZDI-25-374.

Detection Methods for CVE-2025-49217

Indicators of Compromise

• Unusual network traffic patterns to the PolicyServer port from external or untrusted IP addresses
• Unexpected child processes spawned by the PolicyServer service
• Anomalous serialized object payloads in HTTP request bodies to PolicyServer endpoints
• Evidence of reconnaissance activity targeting Trend Micro Endpoint Encryption infrastructure

Detection Strategies

• Monitor PolicyServer network traffic for unusually large or malformed HTTP POST requests containing serialized data
• Implement network intrusion detection rules to identify common deserialization exploit patterns and gadget chain signatures
• Deploy endpoint detection and response (EDR) solutions to detect suspicious process behavior originating from the PolicyServer service
• Configure application logging to capture and alert on deserialization errors or exceptions

Monitoring Recommendations

• Enable verbose logging on the PolicyServer to capture detailed request information
• Monitor system processes for unexpected executables or script interpreters spawned by the PolicyServer process
• Implement network segmentation and monitor traffic flows to/from PolicyServer systems
• Conduct regular log analysis focusing on authentication failures and unusual access patterns

How to Mitigate CVE-2025-49217

Immediate Actions Required

• Apply the security patch provided by Trend Micro immediately as referenced in the Trend Micro Solution Article
• Restrict network access to the PolicyServer to trusted IP addresses and internal networks only
• Implement web application firewall (WAF) rules to filter potentially malicious serialized payloads
• Consider temporarily disabling external access to the PolicyServer until patching is complete

Patch Information

Trend Micro has released a security update to address this vulnerability. Administrators should consult the Trend Micro Solution Article KA-0019928 for detailed patching instructions and download links. Given the critical severity and pre-authentication nature of this vulnerability, immediate patching is strongly recommended.

Workarounds

• Implement strict network access controls to limit connectivity to the PolicyServer to only authorized management systems
• Deploy a reverse proxy or WAF in front of the PolicyServer with rules to inspect and filter incoming requests for deserialization attack patterns
• Segment the PolicyServer network to minimize lateral movement possibilities in case of compromise
• Monitor for and block known deserialization gadget chain patterns at the network perimeter

# Example firewall rule to restrict PolicyServer access (Linux iptables)
# Allow only trusted management subnet to access PolicyServer
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP