The WannaCry ransomware outbreak that struck hundreds of thousands of organizations across the world in May 2017 had happened basically because of organizations failing to apply on time the patches which Microsoft had already released to close the exploit that was instrumental in causing the outbreak. Many big malware strikes that cripple organizations and hit individual users as well happen because of unwarranted delays in software patching. Its always best to change default passwords as soon as you start using a device or any software. Re-using login credentials, especially passwords, is a must for securing accounts and devices.”]
Source: https://hackercombat.com/discussing-common-security-mistakes-and-misconfigurations/