Vulnerability in routers FL MGUARD and TC MGUARD

Advisory Information

• Advisory ID: BOSCH-SA-931197
• CVE Numbers and CVSS v3.1 Scores:
  • CVE-2022-3480
    • Base Score: 7.5 (High)
• Published: 03 Mar 2023
• Last Updated: 03 Mar 2023

Summary

Possible denial of service on HTTPS management interface

The FL MGUARD and TC MGUARD devices sold by Bosch Rexroth are devices from Phoenix Contact that have been introduced as trade goods. A security advisory has been published by the manufacturer, which indicates that a denial of service of the HTTPS management interface of that devices can be triggered by a larger number of unauthenticated HTTPS connections, incoming from different source IP’s [1]. Configuring firewall limits for incoming connections cannot prevent the issue.

During the attack, the HTTPS management interface is no more accessible for valid users. Additionally, there may be an impact on the performance of other services of the FL MGUARD or TC MGUARD device. An unexpected reboot of the device is possible.

Affected Products

• Rexroth FL MGUARD RS2000 TX/& (R911173817) <= 8.9.0
• Rexroth FL MGUARD RS2000 TX/& (R913056204) <= 8.9.0
• Rexroth FL MGUARD RS2000 TX/& (R913058931) <= 8.9.0
• Rexroth FL MGUARD RS4000 TX/& (R901351745) <= 8.9.0
• Rexroth FL MGUARD RS4000 TX/& (R911173814) <= 8.9.0
• Rexroth FL MGUARD RS4000 TX/& (R913076699) <= 8.9.0
• Rexroth FL MGUARD RS4000 VPN& (R901352542) <= 8.9.0
• Rexroth FL MGUARD RS4004 TX/& (R913050362) <= 8.9.0
• Rexroth FL MGUARD RS4004 TX/& (R913051602) <= 8.9.0
• Rexroth FL MGUARD SMART2 VPN& (R911173818) <= 8.9.0
• Rexroth TC MGUARD RS2000 3G & (R911173815) <= 8.9.0
• Rexroth TC MGUARD RS2000 4G & (R913066122) <= 8.9.0
• Rexroth TC MGUARD RS4000 3G & (R911173816) <= 8.9.0
• Rexroth TC MGUARD RS4000 4G & (R901541498) <= 8.9.0

Solution and Mitigations

Update to the latest released version

The vulnerability is fixed in firmware version 8.9.0. We strongly recommend all affected users to upgrade to this or a later version.

Temporary Fix / Mitigation

Don’t allow access to the HTTPS management interface from untrusted networks.

Vulnerability Details

CVE-2022-3480

CVE description: A remote, unauthenticated attacker could cause a denial-of-service of PHOENIX CONTACT FL MGUARD and TC MGUARD devices below version 8.9.0 by sending a larger number of unauthenticated HTTPS connections originating from different source IP’s. Configuring firewall limits for incoming connections cannot prevent the issue.

• Problem Type:
  • CWE-770 Allocation of Resources Without Limits or Throttling
• CVSS Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  • Base Score: 7.5 (High)

Remarks

Security Update Information

With respect to Directive (EU) 2019/770 and Directive (EU) 2019/771 and their national transposition laws, please note:

It is your responsibility to download and/or install any security updates provided by us, for example to maintain product or data security. If you fail to install a security update provided to you within a reasonable period of time, we will not be liable for any product defect solely due to the absence of such security update.

Alternatively, we are entitled to directly download and/or install security updates regardless of your settings. In these cases, we will provide you with the relevant information, e.g. in this security advisory.

CVSS Scoring

Vulnerability classification has been performed using the CVSS v3.1 scoring system . The CVSS environmental score is specific to each customer’s environment and should be defined by the customer to attain a final scoring.

Additional Resources

• [1] Security Advisory for FL MGUARD, TC MGUARD: https://dam-mdc.phoenixcontact.com/asset/156443151564/632a4cc10e4af34cb7b75da31a2f03a1/Security_Advisory_CVE-2022-3480.pdf
• [2] Security Guideline Electric Drives and Controls: https://www.boschrexroth.com/de/de/myrexroth/media-directory-download?object_nr=R911342562

Please contact the Bosch PSIRT if you have feedback, comments, or additional information about this vulnerability at: psirt@bosch.com .

Revision History

• 03 Mar 2023: Initial Publication