Framingham, Mass. -- As e-commerce grows, so do worries about internal security, according to a recent International Data Corp. survey of IT executives at 300 U.S. companies with $100 million or more in revenue. That means an expanding market for Internet security software. ``The increased use of the Internet is clearly seen as both heaven and hell--heaven because electronic commerce can boost revenues and lower costs, hell because it opens up networks and servers to external and, more significantly, internal attacks,'' said Chris Christiansen, program director with IDC's Internet Security service. IDC expects the Internet security software market, which includes firewalls, encryption and antivirus detection, to reach $4.2 billion in 1999 and $7.4 billion by 2002.