SAN FRANCISCO--Symantec has acquired Web security firm Mi5 Networks and plans to announce two new security suites at the RSA security conference on Tuesday.

Mi5 sells a Web security appliance that protects corporations against Web-based threats. Symantec will integrate the technology into its offerings later in 2009 and offer it as a stand-alone product, Joan Fazio, director of product marketing for Symantec Endpoint Security, said in an interview.

The all-cash transaction was completed ...