How Did the Sasser Worm Spread?

Sasser spreads through a Windows vulnerability known as LSASS, or Local Security Authority Subsystem Service. Sasser scans random internet protocol addresses until it finds a vulnerable system. Then it copies itself into the Windows directory as an executable file, and is launched the next time the computer is booted.

How did the Blaster worm spread so quickly?

Once a network (such as a company or university) was infected, it spread quicker within the network because firewalls typically did not prevent internal machines from using a certain port. Filtering by ISPs and widespread publicity about the worm curbed the spread of Blaster.

How did the Internet worm spread?

The worm only targeted computers running a specific version of the Unix operating system, but it spread widely because it featured multiple vectors of attack. For example, it exploited a backdoor in the Internet's electronic mail system and a bug in the “finger” program that identified network users.