Hardcoded Ftp Credentials In Zyxel Nwa/nap/wac Wireless Access Point Series


Hardcoded FTP Credentials


Zyxel NWA/NAP/WAC wireless access point series

Vulnerable Version

see "Vulnerable / tested version"

Fixed Version

see "Solution"

CVE Number







Thomas Weber (Office Vienna) | IoT Inspector | SEC Consult Vulnerability Lab

An FTP-daemon with hardcoded credentials runs on multiple Zyxel WiFi access points from NWA, NAP and WAC series. These credentials can be used to log on to the APs FTP server and steal the configuration file that includes SSIDs and passwords. An attacker could move to protected networks via this way.

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.


Install the newest firmware for your device from the vendor’s website to fix this issue:


Additionally, the vendor provides the following security notice: https://www.zyxel.com/support/hardcoded-FTP-credential-vulnerability-of-access-points.shtml


Restrict network access to the web interface.


Advisory URL



EOF Thomas Weber / @2019


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