PHOENIX CONTACT unauthorized access to WEB-UI on FL NAT SMx

An unauthorized user can get access to the WEB-UI of the device if an authorized IP is used.

VDE-2019-006 (2019-03-25 12:45 UTC+0100)

CVE Identifier

CVE-2019-9744

Affected Vendors

Phoenix Contact

Affected Products

FL NAT SMN 8TX-M (2702443)
FL NAT SMN 8TX-M-DMG (2989352)
FL NAT SMN 8TX (2989365)
FL NAT SMCS 8TX (2989378)

Vulnerability Type

Improper Access Control (CWE-284)

Summary

After login the source IP is used as the session identifier, so that users sharing the same source IP are able to gain full authenticated access to the WEB-UI.

The access attempt will only be successful if the former authorized session has not been terminated by the authorized user or by session timeout.

Impact

If an unauthorized user manages to get access as described above, he gains full access to the device configuration.

Solution

Customers using Phoenix Contact FL NAT SMx devices are recommended to operate the devices in closed networks or protected with a suitable firewall.
For detailed information on our recommendations for measures to protect network-capable devices, please refer to the application note:
https://www.phoenixcontact.com/assets/downloads_ed/local_pc/web_dwl_technical_info/ah_en_ industrial_security_107913_en_01.pdf

To protect the device from an attacker who has gained access to the closed network, or if there is a possibility that multiple users might share a VPN connection with a single endpoint IP, it might be considered to:

  • log off from the WEB-UI immediately after administration
  • disable the WEB-UI and use configuration access via SNMP instead

Reported by

This vulnerability was discovered by Maxim Rupp (rupp.it)