ATTENTION: Remotely exploitable/low skill level to exploit.
Vendor: Rockwell Automation
Equipment: Allen-Bradley MicroLogix 1100 and 1400
Vulnerabilities: Predictable Value Range from Previous Values; Reusing a Nonce, Key Pair in Encryption; Information Exposure; Improper Restriction of Excessive Authentication Attempts; Weak Password Requirements
This advisory was originally posted to the NCCIC Portal on April 25, 2017, and is being released to the ICS-CERT web site.
The following versions of the Allen-Bradley MicroLogix 1100 programmable-logic controller are affected:
The following versions of the Allen-Bradley MicroLogix 1400 programmable logic controller are affected:
Successful exploitation of these vulnerabilities may allow a remote attacker to gain unauthorized access to the affected programmable logic controllers and to spoof or disrupt TCP connections.
Rockwell Automation has released a new firmware version for the Allen-Bradley MicroLogix 1400 Series B controllers, FRN 21.00, to address the identified vulnerabilities. Rockwell Automation encourages users to apply the latest firmware versions that address the identified vulnerabilities.
Rockwell Automation’s new firmware version for the Allen-Bradley MicroLogix 1400 Series B controllers, FRN 21.00, is available at the following location:
There are no firmware versions to address these vulnerabilities in the Allen-Bradley MicroLogix 1100 or MicroLogix 1400 Series A controllers, but Rockwell Automation has offered some compensating controls. Rockwell Automation reports that users can disable the web server on the Allen-Bradley MicroLogix 1100 and 1400 Series A controllers to protect against the exploitation of the improper restriction of excessive authentication attempts and weak password requirements vulnerabilities.
Rockwell Automation recommends that if it is not needed, users should consider disabling the web server to further mitigate these threats.
NCCIC/ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. Specifically, users should:
ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
ICS-CERT 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 ICS‑CERT 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 ICS-CERT for tracking and correlation against other incidents.
In addition, ICS-CERT recommends that users take the following measures to protect themselves from social engineering attacks:
No known public exploits specifically target these vulnerabilities.
Insufficiently random TCP initial sequence numbers are generated, which may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections, resulting in a denial of service for the target device.
The affected product reuses nonces, which may allow an attacker to capture and replay a valid request until the nonce is changed.
User credentials are sent to the web server using the HTTP GET method, which may result in the credentials being logged. This could make user credentials available for unauthorized retrieval.
There are no penalties for repeatedly entering incorrect passwords.
The affected products use a numeric password with a small maximum character size for the password.
These vulnerabilities were reported to ICS-CERT by Rockwell Automation, David Formby and Raheem Beyah of Georgia Tech and Fortiphyd Logic, Inc. Rockwell Automation also reported a vulnerability that was initially identified by Ilya Karpov of Positive Technologies.
Critical Infrastructure Sectors: Food and Agriculture, Water and Wastewater Systems
Countries/Areas Deployed: Worldwide
Company Headquarters Location: Milwaukee, Wisconsin
For any questions related to this report, please contact the CISA at:
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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