CVE-2024-47902: Siemens Intermesh Authentication Bypass

CVE-2024-47902 Overview

A missing authentication vulnerability has been identified in Siemens InterMesh subscriber devices. The web server of affected devices does not authenticate GET requests that execute specific commands (such as ping) on the operating system level. This authentication bypass allows unauthenticated remote attackers to execute system-level commands through the web interface without providing any credentials.

Critical Impact

Unauthenticated remote attackers can execute operating system commands on vulnerable Siemens InterMesh devices through the web server interface, potentially leading to system compromise and lateral movement within industrial networks.

Affected Products

• Siemens InterMesh 7177 Hybrid 2.0 Subscriber (All versions < V8.2.12)
• Siemens InterMesh 7707 Fire Subscriber Firmware (All versions < V7.2.12, only if IP interface is enabled)
• Siemens InterMesh 7707 Fire Subscriber Hardware

Discovery Timeline

• 2024-10-23 - CVE-2024-47902 published to NVD
• 2024-10-30 - Last updated in NVD database

Technical Details for CVE-2024-47902

Vulnerability Analysis

This vulnerability is classified as CWE-306: Missing Authentication for Critical Function. The core issue lies in the web server implementation of the affected InterMesh devices, which fails to enforce authentication for GET requests that trigger operating system-level command execution. Commands such as ping can be executed directly through the web interface without any credential verification, exposing critical diagnostic functionality to unauthorized users.

The InterMesh 7707 Fire Subscriber is only vulnerable when the IP interface is enabled, which is not the default configuration. However, the InterMesh 7177 Hybrid 2.0 Subscriber is vulnerable in all versions prior to V8.2.12 regardless of configuration.

Root Cause

The root cause of this vulnerability is the absence of authentication controls on specific GET request handlers within the web server. The affected endpoints that execute system commands like ping were implemented without access control checks, allowing any network-accessible client to invoke these functions without providing valid credentials.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker with network access to the vulnerable device's web interface can craft HTTP GET requests to invoke system commands. The attack is straightforward:

1. Attacker identifies a vulnerable InterMesh device on the network
2. Attacker sends unauthenticated GET requests to the web server
3. The web server executes the requested command (e.g., ping) at the operating system level
4. The attacker receives command output or confirmation of execution

Since no code examples are available for this vulnerability, organizations should refer to the Siemens Security Advisory SSA-333468 for detailed technical guidance on identifying vulnerable configurations.

Detection Methods for CVE-2024-47902

Indicators of Compromise

• Unexpected HTTP GET requests to the InterMesh web server from unauthorized IP addresses
• Unusual ping or other diagnostic command executions on InterMesh devices
• Web server access logs showing unauthenticated requests to command execution endpoints
• Network traffic anomalies from InterMesh devices to external or unusual internal destinations

Detection Strategies

• Monitor HTTP GET requests to InterMesh device web interfaces for suspicious patterns
• Implement network intrusion detection rules for unauthenticated command execution attempts
• Review web server logs on InterMesh devices for access from unauthorized sources
• Deploy network segmentation monitoring to detect lateral movement from compromised devices

Monitoring Recommendations

• Enable comprehensive logging on InterMesh device web servers
• Implement network traffic analysis for OT/ICS network segments containing InterMesh devices
• Configure alerts for any external network access attempts to InterMesh management interfaces
• Regularly audit device configurations to ensure IP interfaces are disabled on InterMesh 7707 devices when not required

How to Mitigate CVE-2024-47902

Immediate Actions Required

• Upgrade InterMesh 7177 Hybrid 2.0 Subscriber devices to version V8.2.12 or later
• Upgrade InterMesh 7707 Fire Subscriber devices to version V7.2.12 or later
• Disable the IP interface on InterMesh 7707 Fire Subscriber devices if not required
• Restrict network access to InterMesh device web interfaces using firewalls or network segmentation

Patch Information

Siemens has released firmware updates to address this vulnerability. For InterMesh 7177 Hybrid 2.0 Subscriber, update to version V8.2.12 or later. For InterMesh 7707 Fire Subscriber, update to version V7.2.12 or later. Detailed patching guidance is available in the Siemens Security Advisory SSA-333468.

Workarounds

• Disable the IP interface on InterMesh 7707 Fire Subscriber devices (this is the default configuration)
• Implement network segmentation to isolate InterMesh devices from untrusted networks
• Deploy firewall rules to restrict access to the web server interface to authorized management systems only
• Use VPN or other secure access methods for remote administration of InterMesh devices

# Network segmentation example - restrict access to InterMesh management interface
# Apply firewall rules to limit web interface access to trusted management hosts

# Example iptables rule (apply on network firewall/gateway)
iptables -A FORWARD -d <intermesh_device_ip> -p tcp --dport 80 -s <trusted_management_ip> -j ACCEPT
iptables -A FORWARD -d <intermesh_device_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <intermesh_device_ip> -p tcp --dport 443 -s <trusted_management_ip> -j ACCEPT
iptables -A FORWARD -d <intermesh_device_ip> -p tcp --dport 443 -j DROP