CVE-2025-27449: Endress MEAC300 Auth Bypass Vulnerability

CVE-2025-27449 Overview

CVE-2025-27449 is a critical authentication vulnerability affecting the Endress MEAC300-FNADE4 industrial device. The device does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame, making it susceptible to brute-force attacks. This weakness allows unauthenticated remote attackers to repeatedly attempt credential combinations without rate limiting or account lockout mechanisms, potentially leading to unauthorized access to the device.

Critical Impact

An attacker can exploit this vulnerability remotely over the network without requiring any privileges or user interaction, potentially gaining complete control over the industrial device including access to sensitive data, device configuration, and operational controls.

Affected Products

• Endress MEAC300-FNADE4 Firmware (all versions)
• Endress MEAC300-FNADE4 Hardware Device

Discovery Timeline

• 2025-07-03 - CVE-2025-27449 published to NVD
• 2026-02-06 - Last updated in NVD database

Technical Details for CVE-2025-27449

Vulnerability Analysis

This vulnerability is classified under CWE-307 (Improper Restriction of Excessive Authentication Attempts). The Endress MEAC300-FNADE4 device lacks fundamental security controls that would limit the rate or number of authentication attempts. Without these protections, the device allows unlimited login attempts from network-accessible interfaces.

The vulnerability enables attackers to systematically try password combinations until finding valid credentials. Given that industrial devices often use default or weak passwords, this significantly increases the likelihood of successful unauthorized access. The network-accessible nature of the attack surface means that any attacker who can reach the device over the network can attempt exploitation without requiring physical access or prior authentication.

Root Cause

The root cause of this vulnerability is the absence of authentication rate limiting, account lockout policies, or CAPTCHA mechanisms in the MEAC300-FNADE4 firmware. The authentication subsystem accepts and processes login requests without tracking failed attempts or implementing protective delays between consecutive authentication failures. This design oversight allows automated tools to submit thousands of credential combinations per minute without triggering any defensive responses.

Attack Vector

The attack can be conducted remotely over the network (AV:N) with low complexity (AC:L). An attacker requires no prior privileges (PR:N) and no user interaction (UI:N) to exploit this vulnerability. Successful exploitation can result in complete compromise of the device, affecting confidentiality (C:H), integrity (I:H), and availability (A:H) of the system.

An attacker would typically use automated password-cracking tools such as Hydra, Medusa, or custom scripts to systematically enumerate credentials against the device's authentication interface. Common wordlists containing default industrial device credentials and frequently-used passwords would be employed to maximize the chance of successful authentication.

Detection Methods for CVE-2025-27449

Indicators of Compromise

• Unusually high volume of authentication failures from single or multiple IP addresses against MEAC300-FNADE4 devices
• Rapid successive login attempts occurring faster than normal human interaction patterns
• Authentication attempts using known default credential combinations for industrial control devices
• Network traffic patterns showing systematic enumeration behavior against device management interfaces

Detection Strategies

• Deploy network monitoring solutions to detect anomalous authentication traffic patterns targeting ICS/SCADA devices
• Configure SIEM rules to alert on threshold-based authentication failures (e.g., more than 5 failures in 60 seconds from a single source)
• Implement network-level intrusion detection signatures for common brute-force attack tools
• Monitor for connections from known malicious IP addresses or unusual geographic locations

Monitoring Recommendations

• Establish baseline authentication patterns for the MEAC300-FNADE4 devices to identify deviations
• Enable comprehensive logging of all authentication events on network perimeter devices
• Deploy network-based anomaly detection focused on industrial protocol traffic
• Review authentication logs regularly for signs of credential enumeration activity

How to Mitigate CVE-2025-27449

Immediate Actions Required

• Isolate MEAC300-FNADE4 devices from direct internet access using network segmentation
• Implement firewall rules to restrict access to device management interfaces to authorized IP addresses only
• Change all default credentials to strong, unique passwords immediately
• Enable network-level authentication rate limiting using upstream security devices

Patch Information

Consult the vendor security advisories for firmware updates that address this vulnerability. Review the SICK PSIRT Resource and the official security advisory documents available at the SICK CSAF Document (PDF) for current remediation guidance. Additional security best practices for industrial control systems are available from the CISA ICS Recommended Practices.

Workarounds

• Deploy a reverse proxy or network appliance with rate-limiting capabilities in front of the device to throttle authentication attempts
• Implement VPN requirements for all remote access to industrial network segments containing MEAC300-FNADE4 devices
• Use network access control lists (ACLs) to restrict management interface access to specific trusted networks
• Consider deploying an intrusion prevention system (IPS) to automatically block IP addresses exhibiting brute-force behavior

# Example firewall rule to restrict access to management interface
# Replace <MANAGEMENT_PORT> and <TRUSTED_NETWORK> with actual values
iptables -A INPUT -p tcp --dport <MANAGEMENT_PORT> -s <TRUSTED_NETWORK> -j ACCEPT
iptables -A INPUT -p tcp --dport <MANAGEMENT_PORT> -j DROP