Network security threats are increasing as more people and devices connect to networks. The top 10 network security threats according to ITSecurity.com are viruses and worms, Trojan horses, spam, phishing, packet sniffers, maliciously coded websites, password attacks, hardware loss and data fragments, shared computers, and zombie computers/botnets. These threats endanger networks and personal information through methods like installing malicious code, stealing passwords, and hijacking computers remotely. While tools like antivirus software and encryption help mitigate some threats, network security managers still face ongoing challenges to protect systems and data.