ESB-2018.0998 - [Appliance] Siemens TIM: Denial of service - Remote/unauthenticated 2018-04-04

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.0998
              Advisory (ICSA-18-088-02) Siemens TIM 1531 IRC
                               4 April 2018

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        AusCERT Security Bulletin Summary
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Product:           Siemens TIM
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service   -- Remote/Unauthenticated
                   Unauthorised Access -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-4841  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-18-088-02

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Advisory (ICSA-18-088-02) Siemens TIM 1531 IRC

Original release date: March 29, 2018

Legal Notice

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referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For 
more information about TLP, see http://www.us-cert.gov/tlp/.

CVSS v3 9.8

ATTENTION: Exploitable remotely/low skill level to exploit.

Vendor: Siemens

Equipment: TIM 1531 IRC

Vulnerability: Missing Authentication for Critical Function

AFFECTED PRODUCTS

Siemens reports that the vulnerability affects the following TIM 1531 IRC 
communications modules:

    TIM 1531 IRC, all versions prior to v1.1

IMPACT

Successful exploitation may cause the device to enter a denial-of-service 
condition, or allow the attacker to read and manipulate data and configuration
settings of the affected device.

MITIGATION

Siemens recommends updating to version 1.1 as soon as possible. The update can
be found at the following location on the Siemens website:

https://support.industry.siemens.com/cs/ww/en/view/109755374 (link is 
external)

Siemens has identified the following specific workaround and mitigation that 
users can apply to reduce the risk:

    Users can limit access to Port 80/TCP and Port 443/TCP in their network 
infrastructure (e.g., cell protection firewall or corporate firewall) to 
reduce the risk.

Siemens recommends users protect network access with appropriate mechanisms. 
Siemens also advises that users follow recommendations in the product manuals
and configure the operational environment according to Siemens Operational 
Guidelines for Industrial Security:

https://www.siemens.com/cert/operational-guidelines-industrial-security (link
is external)

For more information on this vulnerability and more detailed mitigation 
instructions, please see Siemens Security Advisory SSA-110922 at the following
location:

http://www.siemens.com/cert/advisories (link is external)

NCCIC recommends users take defensive measures to minimize the risk of 
exploitation of this vulnerability. Specifically, users should:

    Minimize network exposure for all control system devices and/or systems, 
and ensure that they are not accessible from the Internet.

    Locate control system networks and remote devices behind firewalls, and 
isolate them from the business network.

    When remote access is required, use secure methods, such as Virtual 
Private Networks (VPNs), recognizing that VPNs may have vulnerabilities and 
should be updated to the most current version available. Also recognize that 
VPN is only as secure as the connected devices.

NCCIC reminds organizations to perform proper impact analysis and risk 
assessment prior to deploying defensive measures.

NCCIC also provides a section for control systems security recommended 
practices on the ICS-CERT web page. Several recommended practices are 
available for reading and download, including Improving Industrial Control 
Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly 
available in the NCCIC Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies, that is available for download from the ICS-CERT website.

Organizations observing any suspected malicious activity should follow their 
established internal procedures and report their findings to NCCIC for 
tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.

VULNERABILITY OVERVIEW

INCORRECT IMPLEMENTATION OF AUTHENTICATION ALGORITHM CWE-303

A remote attacker with network access to Port 80/TCP or Port 443/TCP could 
perform administrative operations on the device without prior authentication.

CVE-2018-4841 has been assigned to this vulnerability. A CVSS v3 base score of
9.8 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

RESEARCHER

Siemens reported this vulnerability to NCCIC.

BACKGROUND

Critical Infrastructure Sectors: Chemical, Critical Manufacturing, and Food 
and Agriculture

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Germany

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