ESB-2018.0308 - [Win] Siemens TeleControl Server Basic: Multiple vulnerabilities 2018-01-31

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.0308
        Advisory (ICSA-18-030-02) Siemens TeleControl Server Basic
                              31 January 2018

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Siemens TeleControl Server Basic
Publisher:         ICS-CERT
Operating System:  Windows
Impact/Access:     Increased Privileges     -- Existing Account      
                   Denial of Service        -- Remote/Unauthenticated
                   Access Confidential Data -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-4837 CVE-2018-4836 CVE-2018-4835

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-18-030-02

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CVSS v3 8.8

ATTENTION: Remotely exploitable/low skill level to exploit.

Vendor: Siemens

Equipment: TeleControl Server Basic

Vulnerabilities: Authentication Bypass Using an Alternate Path or Channel,
Permissions, Privileges, and Access Controls, Resource Exhaustion


AFFECTED PRODUCTS

The following versions of TeleControl Server Basic, a monitoring platform, 
are affected:

    TeleControl Server Basic versions prior to V3.1


IMPACT

Successful exploitation of these vulnerabilities could allow for escalation of
privileges to perform administrative actions.


MITIGATION

Siemens recommends that users install the latest version of TeleControl Server
Basic which can be found at:

https://support.industry.siemens.com/cs/ww/en/view/109755199

Siemens has also identified other mitigations that affected users can take:

    If TeleControl Server Basic is operated in standalone mode, then users can
    close Port 8000/TCP on the Windows firewall to mitigate vulnerabilities
    CVE-2018-4835 and CVE-2018-4836.

    If TeleControl Server Basic is operated in redundancy mode, then users can
    use the Windows firewall to restrict access to Port 8000/TCP to the second
    TeleControl Server Basics' IP address to mitigate vulnerabilities
    CVE-2018-4835 and CVE-2018-4836.

    Users can use the Windows firewall to close Ports 80/TCP and 443/TCP to
    mitigate vulnerability CVE-2018-4837.

For more information on these vulnerabilities and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-65145 at the following
location:

http://www.siemens.com/cert/en/cert-security-advisories.htm (link is external)

NCCIC recommends users take defensive measures to minimize the risk of
exploitation of these vulnerabilities. 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 web site.

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 these vulnerabilities.


VULNERABILITY OVERVIEW

AUTHENTICATION BYPASS USING AN ALTERNATE PATH OR CHANNEL CWE-288

An attacker with network access to Port 8000/TCP could bypass the
authentication mechanism gaining access to limited information.

CVE-2018-4835 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).

PERMISSIONS, PRIVILEGES, AND ACCESS CONTROLS CWE-264

An authenticated attacker with network access to Port 8000/TCP could escalate
privileges and perform administrative operations.

CVE-2018-4836 has been assigned to this vulnerability. A CVSS v3 base score of
8.8 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

UNCONTROLLED RESOURCE CONSUMPTION ('RESOURCE EXHAUSTION') CWE-400

An attacker with access to the TeleControl Server Basic's webserver (Ports
80/TCP or 443/TCP) could cause a Denial-of-Service condition on the web server.
The remaining functionality of the TeleControl Server Basic is not affected by
the Denial-of-Service condition.

CVE-2018-4837 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).


RESEARCHER

Siemens ProductCERT reported the vulnerabilities to NCCIC.


BACKGROUND

Critical Infrastructure Sector: Critical Manufacturing

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Germany

Contact Information

For any questions related to this report, please contact the NCCIC at:

Email: NCCICCUSTOMERSERVICE@hq.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:
http://ics-cert.us-cert.gov
or incident reporting:  https://ics-cert.us-cert.gov/Report-Incident?

The NCCIC continuously strives to improve its products and services. You can
help by choosing one of the links below to provide feedback about this product.

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