CVE-2025-0618: FireEye EDR Agent DoS Vulnerability

CVE-2025-0618 Overview

A persistent denial of service vulnerability exists in the FireEye EDR agent (now Trellix) that allows a malicious third party to disable tamper protection functionality. By sending a specially-crafted tamper protection event to the HX service, an attacker can trigger an exception that prevents any further tamper protection events from being processed. This condition persists even after a system reboot, effectively neutralizing a critical security control.

Critical Impact

Attackers can permanently disable tamper protection on endpoint detection systems, leaving endpoints vulnerable to subsequent attacks without detection or prevention capabilities.

Affected Products

• FireEye EDR Agent (HX Service)
• Trellix EDR Agent

Discovery Timeline

• 2025-04-23 - CVE-2025-0618 published to NVD
• 2025-04-23 - Last updated in NVD database

Technical Details for CVE-2025-0618

Vulnerability Analysis

This vulnerability is classified under CWE-94 (Improper Control of Generation of Code), indicating that the HX service fails to properly validate or sanitize incoming tamper protection events before processing them. The flaw enables an attacker with network access and low-level privileges to send malformed event data that triggers an unhandled exception within the service.

The persistent nature of this vulnerability is particularly concerning for enterprise security. Once triggered, the tamper protection subsystem remains non-functional even after the endpoint is rebooted, suggesting the exception corrupts a persistent state or configuration that is not restored during normal service initialization. This allows attackers to effectively "brick" a critical security component, potentially as a precursor to deploying malware or conducting further attacks on the now-unprotected system.

Root Cause

The root cause lies in improper input validation within the HX service's tamper protection event handler. The service does not adequately validate the structure or content of incoming tamper protection events, allowing malformed data to reach code paths that throw uncaught exceptions. This exception handling failure causes the tamper protection mechanism to enter a permanently failed state that persists across system reboots.

Attack Vector

The attack is network-based and requires only low-level privileges to execute. An attacker with access to the network where the EDR agent operates can craft and send malicious tamper protection events directly to the HX service. No user interaction is required, and the attack can be executed remotely. The persistence of the denial of service condition across reboots amplifies the impact, as remediation requires manual intervention beyond simple system restart.

The vulnerability mechanism involves crafting a tamper protection event with specific malformed data that exploits the input validation weakness. When the HX service processes this event, an exception is triggered that is not properly caught, causing the tamper protection event processing to fail permanently. For technical details on exploitation, see the Trellix Security Article.

Detection Methods for CVE-2025-0618

Indicators of Compromise

• Unexpected cessation of tamper protection event processing on endpoints running FireEye/Trellix EDR agents
• HX service exceptions or crash logs indicating unhandled exceptions during tamper protection event handling
• Endpoints reporting tamper protection as disabled or non-functional without legitimate administrative action

Detection Strategies

• Monitor HX service logs for unhandled exceptions or error states in tamper protection event processing
• Implement alerting on tamper protection status changes across managed endpoints
• Deploy network traffic analysis to identify anomalous or malformed events targeting the HX service
• Correlate endpoint protection status with expected configurations to detect unauthorized modifications

Monitoring Recommendations

• Enable verbose logging for the HX service tamper protection subsystem
• Configure centralized log collection for EDR agent events to identify patterns of exploitation attempts
• Establish baseline behavior for tamper protection event processing and alert on deviations
• Schedule regular health checks for tamper protection functionality across the endpoint fleet

How to Mitigate CVE-2025-0618

Immediate Actions Required

• Review the official Trellix Security Article for vendor-provided remediation guidance
• Audit all endpoints running FireEye/Trellix EDR agents to verify tamper protection functionality is operational
• Implement network segmentation to restrict access to HX service communication channels
• Increase monitoring on endpoints to detect potential exploitation attempts or compromised tamper protection states

Patch Information

Refer to the official Trellix Security Article for patch availability and installation instructions. Organizations should prioritize applying vendor patches as they become available to address this persistent denial of service condition.

Workarounds

• Restrict network access to the HX service ports to trusted management systems only
• Implement firewall rules to filter potentially malicious traffic targeting EDR agent services
• Deploy additional monitoring solutions to detect tampering or security control bypass attempts
• Consider implementing application-level filtering or proxying for events sent to the HX service

Mitigation configurations should be applied according to your organization's security policies and the guidance provided in the Trellix security advisory. Network-level controls can help limit exposure while awaiting official patches.