Chat is a conduit for distribution of malicious code. It's a way to distribute Trojans, and, in addition, users who don't know how to hide their IP address will reveal it during chat. On the Internet, chat is risky business.

Three of the vulnerabilities can launch malicious code that allows an attacker to snoop on users. The other vulnerability is a DOS attack that will only work in a few cases and crash the media player when it tries to open a file.

The problem is that Netscape's implementation of Java did not adhere to Java Sandbox guidelines, which is basically designed to protect users from Java code.

Its transmission technique is somewhat similar to Melissa. Once launched, it downloads an executable backdoor program from one of four Web sites. That program, Win_bug6, steals passwords stored on that computer and sends them to an e-mail address in the Philippines.

There hasn't been a global solution yet to this problem. If hackers can shut down Yahoo!, they can shut down anything they want tomorrow.

It's a serious risk, although the threat has not manifested itself, but it's brand new.