Conficker, also known as Downadup or Kido, is a computer worm that was first detected in November 2008. It exploits vulnerabilities in Microsoft Windows to propagate and form a botnet, infecting millions of computers worldwide. Conficker uses a combination of advanced malware techniques, including disabling security services, blocking access to security websites, and downloading additional malware. Despite efforts to contain it, Conficker remains one of the most notorious worms due to its persistence and widespread impact.