Program Organizational Units (POUs) are block structures used within PLC programming to create programs and projects.[1] POUs can be used to hold user programs written in IEC 61131-3 languages: Structured text, Instruction list, Function block, and Ladder logic.[1] Application - 201203 They can also provide additional functionality, such as establishing connections between the PLC and other devices using TCON.[2]
Stuxnet uses a simple code-prepending infection technique to infect Organization Blocks (OB). For example, the following sequence of actions is performed when OB1 is infected[3]:
*Increase the size of the original block.
*Write malicious code to the beginning of the block.
*Insert the original OB1 code after the malicious code.
References
- John Karl-Heinz. (n.d.). Programming Industrial Automation Systems. Retrieved October 22, 2019.
- Spenneberg, Ralf, Maik Brüggemann, and Hendrik Schwartke. (2016, March 31). Plc-blaster: A worm living solely in the plc.. Retrieved September 19, 2017.
- Nicolas Falliere, Liam O Murchu, Eric Chien. (2011, February). W32.Stuxnet Dossier (Version 1.4). Retrieved September 22, 2017.
Linkede sager
| Linktype | Sag |
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| is related to | Techniques |
| is part of | Execution |
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