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CVE-2023-3595, CVE-2023-3596: Rockwell Automation ControlLogix Vulnerabilities Disclosed

Rockwell Automation issues advisory for multiple vulnerabilities, including a critical flaw that could lead to disruption or destruction of critical infrastructure processes.

Update July 12: The Identifying Affected Systems section has been updated to include a newly released Tenable OT Security plugin as well as updates to our existing plugins for these vulnerabilities.

Background

On July 12, Rockwell Automation published an advisory for multiple vulnerabilities in its Allen-Bradley ControlLogix Communications Modules. ControlLogix Communications Modules are used in many industries and sectors, including energy, transportation and water, among others, to enable communication between machines, IT systems and remote chassis.

CVE Description CVSSv3 Severity
CVE-2023-3595 Rockwell Automation Allen-Bradley ControlLogix Communication Modules Remote Code Execution vulnerability 9.8 Critical
CVE-2023-3596 Rockwell Automation Allen-Bradley ControlLogix Communication Modules Denial of Service vulnerability 7.5 High

It is important to note these modules can be implemented in multiple logical (and physical) configurations. A 1756 ControlLogix Chassis can have up to 17 modules installed in a local chassis. It is common to have multiple network interfaces (physical network cards) configured to bridge and/or segment networks in industrial environments.

Analysis

CVE-2023-3595 is a remote code execution (RCE) vulnerability in Rockwell Automation Allen-Bradley ControlLogix Communication Modules for its 1756 EN2* and 1756 EN3* product families. An attacker could exploit this vulnerability to gain RCE on a vulnerable module by sending specially crafted common industrial protocol (CIP) messages. This risk of exploitation is amplified if the module is not segmented from the internet. Successful exploitation could give an attacker the ability to compromise the memory of a vulnerable module, enabling the attacker to:

  • Manipulate the firmware of a module
  • Add new functionality into a module
  • Wipe the memory of a module
  • Forge traffic between a module
  • Obtain persistence on a module

In addition to the compromise of the vulnerable module itself, the vulnerability could also allow an attacker to affect the industrial process along with the underlying critical infrastructure, which may result in possible disruption or destruction.

CVE-2023-3596 is a denial of service (DoS) vulnerability in Rockwell Automation Allen-Bradley ControlLogix Communication Modules for its 1756 EN4* product family. An attacker could exploit this vulnerability to cause a DoS condition on a target system by sending specially crafted CIP messages to a vulnerable device.

At the time this blog post was published, there was no evidence of active exploitation involving either vulnerability.

Solution

Rockwell Automation has released fixed firmware versions for certain versions of its ControlLogix modules:

ControlLogix catalog

Series

Affected versions

Fixed versions

1756-EN2T
1756-EN2TK
1756-EN2TXT

A,B,C

<=5.008 & 5.028

5.029 for signed version (recommended)
5.009 for unsigned version

D

11.003 and lower

11.004 and later

1756-EN2TP
1756-EN2TPK
1756-EN2TPXT

A

11.003 and lower

11.004 and later

1756-EN2TR
1756-EN2TRK
1756-EN2TRXT

A,B

<=5.008 & 5.028

5.029 for signed version (recommended)
5.009 for unsigned version

C

11.003 and lower

11.004 and later

1756-EN2F
1756-EN2FK

A, B

<=5.008 & 5.028

5.029 for signed version (recommended)
5.009 for unsigned version

C

11.003 and lower

11.004 and later

1756-EN3TR
1756-EN3TRK

A

<=5.008 & 5.028

5.029 for signed version (recommended)
5.009 for unsigned version

B

<=11.003

Update to 11.004 or later

1756-EN4TR
1756-EN4TRK
1756-EN4TRXT

A

<=5.001

Update to 5.002 and later

Some of the best practices include proper segmentation of control networks and utilizing intrusion detection system (IDS) signatures to help identify “anomalous Common Industrial Protocol (CIP)” traffic to vulnerable devices.

Identifying affected systems

To identify affected systems, Tenable has released the following plugins available for Tenable OT Security (formerly Tenable.ot), Tenable Vulnerability Management (formerly Tenable.io), Tenable Security Center (formerly Tenable.sc) and Tenable Nessus:

Plugin ID Title Severity Family
177893 Rockwell Automation ControlLogix Communications Modules Multiple Vulnerabilities Critical SCADA
501226 Rockwell Automation ControlLogix Communications Modules Remote Code Execution (CVE-2023-3595) Critical Tenable OT Security
501228 Rockwell Automation ControlLogix Communications Modules Denial of Service (CVE-2023-3596) High Tenable OT Security

For urgency, Tenable customers can utilize the SCADA plugin to scan for vulnerable devices using Tenable Vulnerability Management, Tenable Security Center and Tenable Nessus. However, for greater visibility regarding the impact to your networks, we strongly encourage customers to utilize our Tenable OT Security plugins. For more information on using Tenable OT Security to identify vulnerable assets, please check out the blog post Finding Rockwell Automation Allen-Bradley Communication Modules Affected By CVE-2023-3595, CVE-2023-3596 in OT Environments.

In addition to these plugins, Tenable Research recommends customers use the following IDS event rule IDs (SIDs) in Tenable OT Security to detect potentially compromised Communications Adapters:

SID Message
1992000 PROTOCOL-SCADA ENIP CIP Socket Object unconnected read with unusual length detected.
1992001 PROTOCOL-SCADA ENIP CIP Socket Object unconnected ucmm read with unusual length detected.
1992002 PROTOCOL-SCADA ENIP CIP Socket Object connected read with unusual length detected.
1992003 PROTOCOL-SCADA ENIP CIP Socket Object connected ucmm read with unusual length detected.
1992004 PROTOCOL-SCADA ENIP CIP Vendor Specific Object unconnected parameter 1 contains unusual length.
1992005 PROTOCOL-SCADA ENIP CIP Vendor Specific Object unconnected parameter 2 contains unusual length.
1992006 PROTOCOL-SCADA ENIP CIP Vendor Specific Object unconnected ucmm parameter 1 contains unusual length.
1992007 PROTOCOL-SCADA ENIP CIP Vendor Specific Object unconnected ucmm parameter 2 with unusual length.
1992008 PROTOCOL-SCADA ENIP CIP Vendor Specific Object connected parameter 1 contains unusual length.
1992009 PROTOCOL-SCADA ENIP CIP Vendor Specific Object connected parameter 2 with unusual length.
1992010 PROTOCOL-SCADA ENIP CIP Vendor Specific Object connected ucmm parameter 1 contains unusual length.
1992011 PROTOCOL-SCADA ENIP CIP Vendor Specific Object connected ucmm parameter 2 contains unusual length.

For more information on how to utilize these SIDs in Tenable OT Security, please refer to the following knowledge base article.

We will update this blog post when/if additional coverage becomes available.

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Change Log

Update July 12: The Identifying Affected Systems section has been updated to include a newly released Tenable OT Security plugin as well as updates to our existing plugins for these vulnerabilities.

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