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SEC Consult Vulnerability Lab Security Advisory < 20190829-0 >  
=======================================================================  
title: Hardcoded FTP Credentials  
product: Zyxel NWA/NAP/WAC wireless access point series  
vulnerable version: see "Vulnerable / tested version"  
fixed version: see "Solution"  
CVE number: -  
impact: medium  
homepage: https://www.zyxel.com  
found: 2019-06-19  
by: Thomas Weber (Office Vienna)  
IoT Inspector  
SEC Consult Vulnerability Lab  
  
An integrated part of SEC Consult  
Europe | Asia | North America  
  
https://www.sec-consult.com  
  
=======================================================================  
  
Vendor description:  
-------------------  
"Focused on innovation and customer-centricity, Zyxel Communications Corp. has  
been connecting people to the internet for nearly 30 years. We keep promoting  
creativity which meets the needs of customers. This spirit has never been  
changed since we developed the world's first integrated 3-in-1 data/fax/voice  
modem in 1992. Our ability to adapt and innovate with networking technology  
places us at the forefront of understanding connectivity for telco/service  
providers, businesses and home users.  
  
We're building the networks of tomorrow, helping unlock the world's potential  
and meeting the needs of the modern workplace; powering people at work, life  
and play. We stand side-by-side with our customers and partners to share new  
approaches to networking that will unleash their abilities. Loyal friend,  
powerful ally, reliable resource โ€” we are Zyxel, Your Networking Ally."  
  
Source: https://www.zyxel.com/about_zyxel/company_overview.shtml  
  
  
  
Business recommendation:  
------------------------  
SEC Consult recommends Zyxel customers to upgrade the firmware to the latest  
version available. A thorough security review should be performed by security  
professionals to identify further potential security issues.  
  
  
Vulnerability overview/description:  
-----------------------------------  
1) Hardcoded FTP Credentials  
An FTP service runs on the Zyxel wireless access point that contains the  
configuration file for the WiFi network. This FTP server can be accessed with  
hardcoded credentials that are embedded in the firmware of the AP.  
When the WiFi network is bound to another VLAN, an attacker can cross the  
network by fetching the credentials from the FTP server.  
  
The credentials were found by doing an automated scan with IoT Inspector.  
  
  
Proof of concept:  
-----------------  
1) Hardcoded FTP Credentials  
The username "devicehaecived" and the password "1234" can be used to access the  
FTP server of the AP on port 21.  
  
The content of the FTP server looks like the following listing:  
-------------------------------------------------------------------------------  
$ ls  
cert conf debug idp packet_trace script tmp wtp_image  
-------------------------------------------------------------------------------  
The directory "conf" contains all configuration files which store the WiFi  
SSIDs and passphrases.  
  
  
Vulnerable / tested versions:  
-----------------------------  
The following versions have been manually tested and were automatically  
verified with IoT Inspector:  
Zyxel NWA5121-NI 5.50 patch 0 and earlier  
Zyxel NWA5121-N 5.50 patch 0 and earlier  
  
The vendor provided the following list of affected devices:  
Zyxel WAC6103D-I 5.50 patch 0 and earlier  
Zyxel WAC6303D-S 5.50 patch 0 and earlier  
Zyxel WAC6502D-E 5.50 patch 0 and earlier  
Zyxel WAC6502D-S 5.50 patch 0 and earlier  
Zyxel WAC6503D-S 5.50 patch 0 and earlier  
Zyxel WAC6553D-E 5.50 patch 0 and earlier  
Zyxel WAC6552D-S 5.50 patch 0 and earlier  
Zyxel WAC5302D-S 5.50 patch 0 and earlier  
Zyxel NWA5123-AC 5.50 patch 0 and earlier  
Zyxel NWA5123-AC HD 5.50 patch 0 and earlier  
Zyxel NWA5123-NI 5.50 patch 0 and earlier  
Zyxel NWA5301-NJ 5.50 patch 0 and earlier  
Zyxel NWA1302-AC 5.50 patch 0 and earlier  
Zyxel NWA1123-ACv2 5.50 patch 0 and earlier  
Zyxel NWA1123-AC HD 5.50 patch 0 and earlier  
Zyxel NWA1123-AC PRO 5.50 patch 0 and earlier  
Zyxel NAP102 5.50 patch 0 and earlier  
Zyxel NAP203 5.50 patch 0 and earlier  
Zyxel NAP303 5.50 patch 0 and earlier  
Zyxel NAP353 5.50 patch 0 and earlier  
  
  
Vendor contact timeline:  
------------------------  
2019-06-26: Contacting vendor through security@zyxel.com.tw.  
2019-06-27: Vendor changed PGP key. Sent advisory with new key. Vendor  
confirmed receipt.  
2019-07-03: Asked for an update; Vendor told that they just finished their  
investigation.  
2019-07-09: Vendor provided a full list of devices that are prone to this  
vulnerability.  
2019-07-23: Asked for a timeline; Vendor asked to shift the release of the  
advisory to 2019-08-29 in order to provide fixes; Shifted advisory  
release to this date.  
2019-08-26: Asked for a status update; Vendor told that fixes are ready to be  
published at 2019-08-29.  
2019-08-29: Coordinated advisory release.  
  
  
Solution:  
---------  
Install the newest firmware for your device from the vendor's website  
to fix this issue:  
  
https://www.zyxel.com/support/download_landing.shtml  
  
Additionally, the vendor provides the following security notice:  
https://www.zyxel.com/support/hardcoded-FTP-credential-vulnerability-of-access-points.shtml  
  
  
Workaround:  
-----------  
Restrict network access to the web interface.  
  
  
Advisory URL:  
-------------  
https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
SEC Consult Vulnerability Lab  
  
SEC Consult  
Europe | Asia | North America  
  
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.  
  
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EOF T. Weber / @2019