CVE-2024-37998: Siemens CPCI85 Auth Bypass Vulnerability

CVE-2024-37998 Overview

A critical authentication bypass vulnerability has been identified in Siemens CPCI85 Central Processing/Communication and SICORE Base system products. The vulnerability allows an unauthorized attacker to reset the password of administrative accounts without requiring knowledge of the current password when the auto login feature is enabled. This security flaw could enable attackers to obtain full administrative access to affected applications, potentially leading to complete system compromise.

Critical Impact

Unauthorized attackers can gain administrative access by resetting admin passwords without authentication when auto login is enabled, potentially leading to complete system takeover.

Affected Products

• CPCI85 Central Processing/Communication (All versions < V5.40)
• SICORE Base system (All versions < V1.4.0)

Discovery Timeline

• 2024-07-22 - CVE-2024-37998 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-37998

Vulnerability Analysis

This vulnerability is classified under CWE-620 (Unverified Password Change), which describes a weakness where an application allows users to change passwords without first requiring verification of the original password. In the context of CVE-2024-37998, the affected Siemens industrial control systems fail to properly authenticate password reset requests when the auto login feature is enabled.

The attack can be executed remotely over the network without requiring any prior authentication or user interaction. Successful exploitation grants the attacker full administrative privileges over the affected industrial control systems, enabling them to modify configurations, access sensitive data, or disrupt critical operations.

Root Cause

The root cause of this vulnerability lies in the improper implementation of the password change mechanism within the affected Siemens products. When auto login is enabled, the system bypasses the standard authentication verification that would normally require users to provide their current password before setting a new one. This design flaw creates a security gap that allows unauthorized password resets.

The CWE-620 classification indicates that the system fails to verify the identity of the user requesting the password change, allowing any network-accessible attacker to exploit this weakness when the auto login configuration is active.

Attack Vector

The vulnerability is exploitable via network access without requiring authentication or user interaction. An attacker with network access to the affected system can initiate a password reset for administrative accounts. The key conditions for exploitation include:

1. The target system must have the auto login feature enabled
2. The attacker must have network connectivity to the affected device
3. No authentication credentials are required to initiate the attack

Once the attacker successfully resets the administrative password, they gain complete control over the affected industrial control system. This could lead to unauthorized configuration changes, operational disruptions, or access to sensitive industrial process data.

Detection Methods for CVE-2024-37998

Indicators of Compromise

• Unexpected password reset events or authentication changes for administrative accounts
• Administrative access from unrecognized IP addresses or during unusual hours
• Configuration changes to the auto login feature or authentication settings
• Unauthorized modifications to system configurations or user accounts

Detection Strategies

• Monitor authentication logs for password reset attempts, particularly for administrative accounts
• Implement network traffic analysis to detect unauthorized access attempts to management interfaces
• Configure alerts for administrative credential changes without corresponding legitimate change requests
• Review audit logs for sequential failed logins followed by successful password resets

Monitoring Recommendations

• Enable comprehensive logging on all CPCI85 and SICORE Base system deployments
• Implement network segmentation to isolate industrial control systems from general network traffic
• Deploy intrusion detection systems configured to monitor traffic patterns to affected devices
• Establish baseline behavior patterns for administrative access and alert on anomalies

How to Mitigate CVE-2024-37998

Immediate Actions Required

• Disable the auto login feature on all affected CPCI85 and SICORE Base system deployments immediately
• Upgrade CPCI85 Central Processing/Communication to version V5.40 or later
• Upgrade SICORE Base system to version V1.4.0 or later
• Implement network segmentation to restrict access to affected systems from untrusted networks

Patch Information

Siemens has released security updates to address this vulnerability. Detailed patch information and remediation guidance is available in the Siemens Security Advisory SSA-071402. Organizations should upgrade to the following patched versions:

• CPCI85 Central Processing/Communication: Version V5.40 or later
• SICORE Base system: Version V1.4.0 or later

Workarounds

• Disable the auto login feature on all affected systems if upgrading is not immediately possible
• Implement strict network access controls to limit connectivity to affected devices
• Enable multi-factor authentication for administrative access where supported
• Monitor administrative accounts for unauthorized password changes or access attempts

# Network segmentation example using firewall rules
# Restrict access to CPCI85/SICORE management interfaces to authorized networks only
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP