Prior to the discovery of the [[Stuxnet]] [[computer worm]] in June 2010, the security of PLCs received little attention. Modern programmable controllers generally contain real-time operating systems, which can be vulnerable to exploits in a similar way as desktop operating systems, like [[Microsoft Windows]]. PLCs can also be attacked by gaining control of a computer they communicate with.<ref name=":5">{{cite web |url=http://www.tofinosecurity.com/blog/plc-security-risk-controller-operating-systems |title=PLC Security Risk: Controller Operating Systems - Tofino Industrial Security Solution |website=TofinoSecurity.com |date=May 2011 |author=Byres}}</ref> {{As of|2011|since=y|post=,}} these concerns have grown – networking is becoming more commonplace in the PLC environment, connecting the previously separated plant floor networks and office networks.<ref>{{Harvnb|Bolton|2015|p=15}}</ref>
In February 2021, [[Rockwell Automation]] publicly disclosed a critical vulnerability affecting its Logix controllers family. The [[Key (cryptography)|Secretsecret cryptographic key]] used to [[Symmetric-key algorithm|verify communication]] between the PLC and workstation cancould be extracted from the programming software (Studio 5000 Logix Designer programming software) and used to remotely change program code and configuration of a connected controller. The vulnerability was given a severity score of 10 out of 10 on the [[Common Vulnerability Scoring System|CVSS vulnerability scale]]. At the time of writing, the mitigation of the vulnerability was to [[Defense in depth (computing)|limit network access to affected devices]].<ref>{{Cite web|last=Goodin|first=Dan|date=2021-02-26|title=Hard-coded key vulnerability in Logix PLCs has severity score of 10 out of 10|url=https://arstechnica.com/information-technology/2021/02/hard-coded-key-vulnerability-in-logix-plcs-has-severity-score-of-10-out-of-10/|access-date=2021-03-07|website=Ars Technica }}</ref><ref>{{Cite web |last=Li |first=Tom |date=2021-03-01 |title=Max level vulnerability found in Logix PLCs {{!}} IT World Canada News |url=https://www.itworldcanada.com/article/max-level-vulnerability-found-in-logix-plcs/443152,%20https://www.itworldcanada.com/article/max-level-vulnerability-found-in-logix-plcs/443152 |access-date=2021-03-07 |website=ITWorldCanada.com }}</ref>
