Organizations responsible for SCADA systems security should take Stuxnet seriously; it exploits multiple attack vectors and clearly illustrates the vulnerabilities of SCADA systems. There are two things that make Stuxnet unique. One is the zero day it exploits in the LNK functionality (while many pieces of malware utilize zero days when initially identified, SCADA systems have never been exploited in this way before, and chances are it won't be the last time either). The other is that the malware was signed by Realtek as trusted software, meaning that part of the attack involved stealing a code-signing certificate from Realtek -- and the certificate used to sign the code wasn't revoked until news coverage prompted the revocation. Signed code is supposed to help protect systems from malware, but Stuxnet pointed out deficiencies in this type of protection.
The security community at large should take Stuxnet seriously as well because of the sophistication of the attack and the security vulnerabilities it was able to exploit. For home users or enterprises that don't manage SCADA systems, the risk is fairly low and patches have been released by Microsoft and other information security systems that include protections, like antimalware definitions.
This was first published in August 2010