CVE-2025-29269: Allnet All-rut22gw Firmware RCE Flaw

CVE-2025-29269 Overview

CVE-2025-29269 is a critical OS command injection vulnerability affecting the ALLNET ALL-RUT22GW industrial LTE cellular router. The vulnerability exists in the popen.cgi endpoint, where the command parameter fails to properly sanitize user-supplied input before passing it to system shell functions. This allows unauthenticated remote attackers to execute arbitrary operating system commands with the privileges of the web server process.

Industrial routers like the ALL-RUT22GW are commonly deployed in critical infrastructure environments, including manufacturing facilities, remote monitoring stations, and IoT gateway deployments. The network-accessible nature of this vulnerability, combined with no authentication requirements, makes it particularly dangerous in environments where these devices may be exposed to untrusted networks.

Critical Impact

Unauthenticated remote attackers can execute arbitrary OS commands on affected ALLNET ALL-RUT22GW devices, potentially leading to complete device compromise, network pivoting, and disruption of industrial operations.

Affected Products

• ALLNET ALL-RUT22GW Firmware version 3.3.8
• ALLNET ALL-RUT22GW Hardware Device

Discovery Timeline

• 2025-12-04 - CVE-2025-29269 published to NVD
• 2025-12-16 - Last updated in NVD database

Technical Details for CVE-2025-29269

Vulnerability Analysis

This vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The flaw resides in the popen.cgi CGI script, which is part of the router's web management interface.

When processing requests to the popen.cgi endpoint, the application takes user-supplied data from the command parameter and incorporates it directly into a system command execution context without adequate input validation or sanitization. This architectural flaw allows attackers to inject shell metacharacters and additional commands that are then executed by the underlying operating system.

The vulnerability can be exploited remotely over the network without any prior authentication, making it accessible to any attacker who can reach the device's web interface. Successful exploitation grants the attacker the ability to execute commands with the same privileges as the web server process, which in embedded devices like industrial routers often runs with elevated or root privileges.

Root Cause

The root cause of this vulnerability is the failure to implement proper input validation and sanitization on the command parameter before it is passed to operating system command execution functions. The popen.cgi script likely uses functions such as popen(), system(), or similar shell-invoking mechanisms that interpret shell metacharacters.

Without proper escaping or allowlist-based validation, special characters like semicolons (;), pipes (|), backticks (`), and command substitution sequences ($(...)) can be used to break out of the intended command context and inject additional malicious commands.

Attack Vector

The attack vector is network-based and requires no authentication. An attacker can craft malicious HTTP requests to the popen.cgi endpoint, embedding OS commands within the command parameter. The injected commands may include shell metacharacters that allow command chaining or command substitution.

Typical attack scenarios include:

• Establishing reverse shells to gain persistent interactive access
• Downloading and executing malware or backdoors
• Exfiltrating sensitive configuration data including credentials
• Modifying device configurations to pivot into connected networks
• Disrupting industrial processes connected through the router

For detailed technical analysis and exploitation scenarios, refer to the ByteRay security research blog.

Detection Methods for CVE-2025-29269

Indicators of Compromise

• Unusual HTTP requests to /popen.cgi or similar CGI endpoints containing shell metacharacters
• Unexpected outbound network connections from the router to unknown external IP addresses
• Presence of unauthorized files or scripts in the router's filesystem
• Unexpected processes running on the device, particularly shells or download utilities
• Changes to device configuration that were not authorized by administrators

Detection Strategies

• Monitor web server access logs for requests to popen.cgi containing suspicious characters such as ;, |, &, `, $(), or encoded variants
• Deploy network intrusion detection signatures to identify command injection payloads in HTTP traffic destined for ALL-RUT22GW devices
• Implement web application firewall (WAF) rules to block requests containing OS command injection patterns
• Use network behavior analysis to detect anomalous outbound connections from industrial router segments

Monitoring Recommendations

• Establish baseline network behavior for ALL-RUT22GW devices and alert on deviations
• Configure centralized logging to capture all HTTP requests to device management interfaces
• Implement real-time alerting for any access to CGI endpoints from unauthorized source IP addresses
• Regularly audit device configurations for unauthorized changes

How to Mitigate CVE-2025-29269

Immediate Actions Required

• Immediately restrict network access to the ALL-RUT22GW web management interface to trusted administrative IP addresses only
• Place affected devices behind a firewall that blocks external access to the management interface
• Audit device logs for any evidence of exploitation attempts or compromise
• If compromise is suspected, isolate the device and perform forensic analysis before remediation
• Contact ALLNET support to inquire about firmware updates addressing this vulnerability

Patch Information

At the time of publication, no vendor patch has been publicly announced for this vulnerability. Organizations should monitor the ALLNET website and the ALL-RUT22GW product page for security advisories and firmware updates. When a patch becomes available, apply it immediately following proper change management procedures.

Workarounds

• Implement strict network segmentation to isolate ALL-RUT22GW devices from untrusted networks
• Use VPN or other secure access methods for remote management instead of exposing the web interface directly
• Deploy a reverse proxy with input filtering capabilities in front of the device management interface
• Disable the web management interface entirely if remote management is not required
• Consider replacing affected devices with alternative solutions until a patch is available

# Example: Firewall rule to restrict management access (iptables)
# Allow management access only from trusted admin network
iptables -A INPUT -p tcp --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP