The following code is for security research and authorized testing only.
python
# CVE-2026-20833 PoC - Windows Kerberos Weak Cryptographic Algorithm Exploitation
# This PoC demonstrates the concept of exploiting weak cryptographic algorithms in Windows Kerberos
import os
import sys
import subprocess
import re
def check_kerberos_encryption_algorithms():
"""
Check for weak Kerberos encryption algorithm configurations
This script checks for the presence of deprecated or weak encryption types
"""
print("[*] CVE-2026-20833 - Windows Kerberos Weak Encryption Algorithm Check")
print("[*] Target: Windows Kerberos Authentication Service")
print("=" * 60)
# Check for weak encryption types in Kerberos configuration
weak_algorithms = [
"des-cbc-crc", # DES encryption - considered weak
"des-cbc-md5", # DES encryption - considered weak
"rc4-hmac", # RC4 encryption - known weaknesses
"des3-cbc-sha1" # 3DES - deprecated in modern systems
]
print("\n[+] Checking for weak Kerberos encryption algorithms...")
try:
# Use klist to display cached Kerberos tickets
result = subprocess.run(['klist', 'tickets'], capture_output=True, text=True, timeout=30)
print(f"[+] Cached tickets information:\n{result.stdout}")
# Check for weak encryption types in ticket output
for algorithm in weak_algorithms:
if algorithm.upper() in result.stdout.upper():
print(f"[!] WARNING: Weak encryption algorithm detected: {algorithm}")
except FileNotFoundError:
print("[-] klist command not found - this system may not support Kerberos")
except Exception as e:
print(f"[-] Error accessing Kerberos tickets: {e}")
print("\n[*] Note: This is a demonstration script for security research purposes")
print("[*] Actual exploitation requires specific conditions and weak encryption configuration")
print("[*] Mitigation: Apply Microsoft security updates and disable weak encryption types")
def demonstrate_vulnerability():
"""
Simulate vulnerability detection for educational purposes
"""
print("\n[*] Simulating vulnerability assessment...")
print("[+] Checking Kerberos encryption settings via registry...")
# In a real scenario, this would check:
# HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps
# Or Kerberos policy settings
print("[+] Querying supported encryption types...")
print("[+] Checking for legacy encryption protocol support...")
# Simulated check results
print("[+] Supported encryption types: AES256-CTS-HMAC-SHA1-96 (Strong)")
print("[+] Supported encryption types: AES128-CTS-HMAC-SHA1-96 (Strong)")
print("[+] Legacy encryption types: RC4-HMAC (Weak - VULNERABLE)")
print("[+] Legacy encryption types: DES-CBC-CRC (Weak - VULNERABLE)")
print("\n[!] VULNERABILITY DETECTED: System supports weak encryption algorithms")
print("[!] Attack complexity: Low (AV:L/PR:L/UI:N)")
print("[!] Confidentiality impact: High (C:H)")
if __name__ == "__main__":
print("CVE-2026-20833 - Windows Kerberos Weak Cryptographic Algorithm")
print("Use of broken or risky cryptographic algorithm in Windows Kerberos")
print("CVSS 3.1: 5.5 (Medium)")
print()
check_kerberos_encryption_algorithms()
demonstrate_vulnerability()
print("\n[*] For official remediation, refer to Microsoft Security Response Center")
print("[*] Reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20833")