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Rockwell Automation Addresses Flaws in Programmable Controllers

Several vulnerabilities have been found in Allen-Bradley programmable automation controllers, programmable logic controllers and safety programmable controllers from Rockwell Automation.

According to ICS-CERT, a critical stack-based buffer overflow flaw affects several controllers running firmware versions 16 through 21, including ControlLogix, GuardLogix, FlexLogix, CompactLogix, SoftLogix and RSLogix controllers.

The security hole, tracked as CVE-2016-9343, can be exploited to execute arbitrary code on the controller or cause the device to enter a denial-of-service (DoS) condition. A remote attacker can exploit the vulnerability by sending specially crafted common industrial protocol (CIP) packets to the targeted system.

Rockwell Automation has released firmware updates that address this flaw for most of the affected products, except FlexLogix controllers, which are no longer supported. The company has also advised customers to use firewalls to block requests from untrusted sources, and keep the controllers in RUN mode rather than Remote RUN or Remote Program modes in order to prevent unauthorized changes.

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A separate advisory published by ICS-CERT last week describes two low and medium severity issues affecting MicroLogix 1100 and 1400 PLCs.

One of the vulnerabilities, identified as CVE-2016-9334, allows a man-in-the-middle (MitM) attacker to intercept user credentials in clear text as they travel from the web browser to the server.

The second flaw, tracked as CVE-2016-9338, allows a user with admin privileges to remove all administrative users from the web server, requiring a factory reset to restore ancillary functionality. ICS-CERT has pointed out that exploitation of this vulnerability does not affect the device’s controller functionality.

Rockwell Automation has released firmware versions 15.000 and 16.000 to address these vulnerabilities in MicroLogix 1100 and 1400 series B controllers. However, the flaws have not been patched in MicroLogix 1100 and 1400 series A controllers. As a workaround, users have been advised to disable the web server to prevent exploitation of these flaws.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.