Using Tofino to Control the Spread of Stuxnet Malware

Overview:

This application note describes how to use the Tofino Industrial Security Solution to prevent the spread of the Stuxnet worm in both Siemens and non-Siemens network environments.

What is Stuxnet?
Stuxnet is a computer worm designed to target one or more industrial systems that use Siemens PLCs. The objective of this malware appears to be to destroy specific industrial processes.

Stuxnet will infect Windows-based computers on any control or SCADA system, regardless of whether or not it is a Siemens system. The worm only attempts to make modifications to controllers that are model S7-300 or S7-400 PLCs. However, it is aggressive on all networks and can negatively affect any control system. Infected computers may also be used as a launch point for future attacks.

How Stuxnet Spreads
Stuxnet is one of the most complex and carefully engineered worms ever seen. It takes advantage of at least four previously unknown vulnerabilities, has multiple propagation processes and shows considerable sophistication in its exploitation of Siemens control systems.

A key challenge in preventing Stuxnet infections is the large variety of techniques it uses for infecting other computers. It has three primary pathways for spreading to new victims:
- via infected removable USB drives;
- via Local Area Network communications
- via infected Siemens project files

Within these pathways, it takes advantage of seven independent mechanisms to spread to other computers.

Stuxnet also has a P2P (peer-to-peer) networking system that automatically updates all installations of the Stuxnet worm in the wild, even if they cannot connect back to the Internet. Finally, it has an Internet-based command and control mechanism that is currently disabled, but could be reactivated in the future.

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Author: Tofino  | File Type: PDF

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