CVE-2024-47945: Rittal IoT Interface Auth Bypass Flaw

CVE-2024-47945 Overview

CVE-2024-47945 is a critical session hijacking vulnerability affecting Rittal IoT Interface and CMC III Processing Units firmware. The devices are vulnerable due to insufficient entropy in the session ID generation algorithm. The session IDs are predictable, with only 32,768 possible values per user, which allows attackers to pre-generate valid session IDs, leading to unauthorized access to user sessions. This weakness stems from the use of an insecure rand() function call combined with missing initialization via srand(). As a result, only the process IDs (PIDs) are effectively used as the seed, making session tokens highly predictable.

Critical Impact

Attackers can hijack authenticated user sessions by pre-computing the limited set of possible session IDs, gaining unauthorized access to critical IoT infrastructure management interfaces without valid credentials.

Affected Products

• Rittal IoT Interface Firmware
• Rittal IoT Interface (Hardware)
• Rittal CMC III Processing Units Firmware
• Rittal CMC III Processing Units (Hardware)

Discovery Timeline

• 2024-10-15 - CVE CVE-2024-47945 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-47945

Vulnerability Analysis

This vulnerability represents a fundamental cryptographic weakness in session management for Rittal IoT devices. The session ID generation mechanism relies on the C standard library's rand() function, which is inherently unsuitable for security-sensitive applications. More critically, the implementation fails to properly seed the random number generator using srand() with an unpredictable value. This oversight means the pseudo-random number generator (PRNG) produces predictable sequences based solely on the process ID (PID) of the running application.

Since PIDs on Linux-based systems typically range from 1 to 32,768 (the default /proc/sys/kernel/pid_max value), the entire session ID space is effectively limited to this range. An attacker can enumerate all possible session IDs in advance and attempt to hijack active sessions through brute-force correlation.

Root Cause

The root cause is classified under CWE-340 (Generation of Predictable Numbers or Identifiers) and CWE-331 (Insufficient Entropy). The firmware developers used a cryptographically weak random number generator (rand()) for security-critical session token generation. The absence of proper seeding via srand() with a high-entropy source (such as /dev/urandom or system entropy pools) further compounds the weakness. Instead, the default behavior causes the PRNG to be implicitly seeded only with the PID value, creating a trivially predictable session ID space.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability remotely by:

1. Enumerating all 32,768 possible session ID values based on PID-seeded rand() output
2. Generating a lookup table mapping PIDs to their corresponding session ID sequences
3. Attempting session hijacking by submitting pre-computed session IDs to the device's web interface
4. Once a valid session ID is matched to an active authenticated session, the attacker gains full access with the victim's privileges

The predictable nature of the session IDs allows attackers to pre-generate valid tokens without observing any network traffic, making this attack feasible even against well-protected network segments.

Detection Methods for CVE-2024-47945

Indicators of Compromise

• Unusual session activity from multiple IP addresses using the same session ID
• High volume of authentication-related requests attempting different session tokens
• Multiple failed session validation attempts followed by successful access
• Anomalous geographic or network origin for authenticated management sessions

Detection Strategies

• Monitor web server logs for rapid sequential session ID submissions indicative of brute-force attempts
• Implement session binding to client IP address and user-agent to detect session reuse from different contexts
• Deploy network intrusion detection rules to identify patterns of session enumeration attacks
• Correlate authentication logs with session activity to identify sessions accessed without corresponding login events

Monitoring Recommendations

• Enable verbose logging on Rittal IoT Interface and CMC III devices for session-related events
• Configure SIEM alerts for abnormal session creation or access patterns
• Monitor for unauthorized administrative actions that may indicate compromised sessions
• Implement network segmentation and monitor traffic to critical IoT infrastructure management interfaces

How to Mitigate CVE-2024-47945

Immediate Actions Required

• Isolate affected Rittal IoT Interface and CMC III Processing Units from untrusted network segments
• Restrict network access to device management interfaces using firewall rules and access control lists
• Implement VPN or jump host requirements for administrative access to affected devices
• Enable additional authentication factors where supported to reduce session hijacking impact
• Review and audit existing session activity for signs of unauthorized access

Patch Information

Organizations should consult Rittal Product Information for official firmware updates addressing this vulnerability. Additionally, the SEC Consult Rittal IoT Report provides detailed technical analysis, and the Full Disclosure Email Thread contains additional disclosure information. Contact Rittal support directly to obtain the latest firmware versions that implement cryptographically secure session ID generation.

Workarounds

• Deploy a web application firewall (WAF) in front of affected devices to detect and block session brute-force attempts
• Implement network-level access controls limiting management interface access to specific trusted IP addresses
• Configure session timeouts to minimize the window of opportunity for session hijacking attacks
• Use network segmentation to isolate IoT infrastructure from general corporate networks
• Consider deploying a reverse proxy with additional session validation and rate limiting capabilities

# Example network isolation using iptables
# Restrict access to Rittal device management port (adjust IP and port as needed)
iptables -A INPUT -p tcp --dport 443 -s 192.168.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Log potential brute-force attempts
iptables -A INPUT -p tcp --dport 443 -m limit --limit 10/minute -j LOG --log-prefix "RITTAL_ACCESS: "