ICS Alert (ICS-ALERT-11-256-05A)

Rockwell Automation RSLogix Overflow Vulnerability (UPDATE A)

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This Alert Update is a follow-up to the original ICS-CERT Alert titled “ICS-ALERT-11-256-05—ROCKWELL RSLOGIX OVERFLOW VULNERABILITY” that was published September 13, 2011, on the ICS-CERT web page.

ICS-CERT is aware of a public report of an overflow vulnerability with proof-of-concept (POC) exploit code affecting the Rockwell RSLogix 5000, Version 19. According to this report, services running on Port 4446 are vulnerable to a memory overflow. This report was released without coordination with either the vendor or ICS-CERT.

ICS-CERT has not yet verified the vulnerabilities or POC code, but has reached out to the affected vendor to notify, confirm, and identify mitigations. ICS-CERT is issuing this alert to provide early notice of the report and identify baseline mitigations for reducing risks to these and other cybersecurity attacks.

----- BEGIN UPDATE 1 of 3 -----

Rockwell has released the following advisories:

Security Advisory Index: http://rockwellautomation.custhelp.com/app/answers/detail/a_id/54102

FactoryTalk RnaUtility.dll Vulnerability September 16, 2011, Advisory: http://rockwellautomation.custhelp.com/app/answers/detail/a_id/456144

----- END UPDATE 1 of 3 -----

The report included vulnerability details and POC exploit code for the following vulnerability:

Vulnerability TypeExploitabililtyImpact
OverflowRemoteDenial of Service
Text 2AText 2BText 2C

Please report any issues affecting control systems in critical infrastructure environments to ICS-CERT.


Rockwell Automation provides industrial automation control and information products worldwide, across a wide range of industries.

The Rockwell RSLogix family is a group of ladder logic programming packages that operates on
Microsoft Windows operating systems.

----- BEGIN UPDATE 2 of 3 -----

RSLogix 5000 supports the Allen-Bradley ControlLogix and GuardLogix family of programmable

----- END UPDATE 2 of 3 -----


ICS-CERT released a follow-up advisory, ICSA-11-273-03 - Rockwell RSLogix Overflow Vulnerability, on September 30, 2011.


----- BEGIN UPDATE 3 of 3 -----

Rockwell Automation is aware of this vulnerability and plans to release a software patch within 14 days. Rockwell recommends configuring firewalls to block the following TCP ports to prevent traversal of RNA messages in and out of the ICS system:

  • 1330
  • 1331
  • 1332
  • 4241
  • 4242
  • 4446
  • 6543
  • 9111
  • 60093
  • 49281.

Rockwell also recommends users evaluate firewall configurations to ensure other appropriate inbound and
outbound traffic is blocked.

MITRE has assigned number CVE-2011-3489 to this vulnerability.

----- END UPDATE 3 of 3 -----

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these
vulnerabilities. Specifically, users should:

  • Minimize network exposure for all control system devices. Control system devices should not directly face the Internet.a
  • Locate control system networks and devices behind firewalls, and isolate them from the business network.
  • If remote access is required, employ secure methods such as Virtual Private Networks (VPNs).

ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to taking defensive measures.

The Control System Security Program also provides a recommended practices section for control systems on the US-CERT website. Several recommended practices are available for reading or download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Organizations that observe any suspected malicious activity should follow their established internal procedures and report their findings to ICS-CERT for tracking and correlation against other incidents.

Contact Information

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

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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