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 — 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


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SEC Consult
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EOF T. Weber / @2019