ESB-2019.0396 - [Appliance] Siemens SICAM A8000 RTU Series: Denial of service - Remote/unauthenticated 2019-02-08

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0396
                         Advisory (ICSA-19-038-01)
                              8 February 2019

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        AusCERT Security Bulletin Summary
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Product:           Siemens SICAM A8000 RTU Series
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-13798  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-19-038-01

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Advisory (ICSA-19-038-01)

Siemens SICAM A8000 RTU Series

Original release date: February 07, 2019

Legal Notice

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1. EXECUTIVE SUMMARY

  o CVSS v3 5.3
  o ATTENTION: Exploitable remotely/low skill level to exploit
  o Vendor: Siemens
  o Equipment: SICAM A8000 RTU
  o Vulnerability: Uncaught Exception

2. RISK EVALUATION

The SICAM A8000 RTU series is affected by a security vulnerability that could
allow unauthenticated remote users to cause a denial-of-service condition on
the web server of affected products.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SICAM A8000 RTU, a telecontrol and automation device,
are affected:

  o SICAM A8000 CP-8000 versions prior to v14,
  o SICAM A8000 CP-802X versions prior to v14, and
  o SICAM A8000 CP-8050 versions prior to v2

3.2 VULNERABILITY OVERVIEW

3.2.1 UNCAUGHT EXCEPTION CWE-248

Specially crafted network packets sent to Ports 80/TCP or 443/TCP could allow
an unauthenticated remote attacker to cause a denial-of-service condition on a
web server.

CVE-2018-13798 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 ).

3.3 BACKGROUND

  o CRITICAL INFRASTRUCTURE SECTORS: Energy
  o COUNTRIES/AREAS DEPLOYED: Worldwide
  o COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Emanuel Duss and Nicolas Heiniger from Compass Security reported this
vulnerability to Siemens.

4. MITIGATIONS

Siemens has released updates for all product variants and recommends users
update to the new versions:

https://support.industry.siemens.com/cs/searchsearch=a8000%20cp8000

Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:

  o Limit access to the web server on Ports 80/TCP and 443/TCP with an external
    firewall.
  o Apply a Defense-in-Depth strategy.

For additional information see Siemens' security advisory SSA-579309 at the
following location:

http://www.siemens.com/cert/en/cert-security-advisories.htm

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

  o Minimize network exposure for all control system devices and/or systems,
    and ensure that they are not accessible from the Internet .
  o Locate control system networks and remote devices behind firewalls, and
    isolate them from the business network.
  o 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
on the ICS-CERT website in the Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies .

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.

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