Simplify the following text for a Grade 12 native English-speaking person.
Original: Code Red and Code Red II were famous ( and much discussed ) worms that exploited vulnerabilities of the Windows Indexing Service of Windows 2000 's Internet Information Services ( IIS ) .
Simplified: Code Red and Code Red II were famous computer worms that used problems with indexing service of Windows 2000 's Internet Information Services ( IIS ) to caused a security problem .