If you receive an e-mail offering a download of Internet Explorer 7 Beta 2, delete it. A new virus is making the rounds that comes disguised as a test version of Microsoft current Web browser.

Security experts reported no widespread damage Friday morning, but they said the virus is notable for a couple of reasons. The e-mail includes a convincing graphic that looks like it could really be from Microsoft, and the virus is delivered when recipients click on a link rather than in an attachment, which makes it harder to stop it from reaching in-boxes.

"The idea of sending a link seems to be a trend among attackers; it's still fairly new and it works much better than sending a file," said Mikko Hypponen, chief research officer at F-Secure.

The e-mails carry the subject line "Internet Explorer 7 Downloads" and appear to come from admin@microsoft.com. They include a blue, Microsoft-style graphic offering a download of IE 7 beta 2. Clicking the graphic will download an executable file called IE 7.exe.

The file is actually a new virus called Virus.Win32.Grum.A, and security experts were still analyzing it Friday to see what it does. Sophos PLC said it can spread by e-mailing itself to contacts in a user's address book. The virus tampers with registry files to ensure it gets installed, and it tries to download additional files from the Internet, said Graham Cluley, a senior technology consultant for Sophos.

Other specifics were unknown yet, but such viruses often install a keystroke logger to steal personal information, and establish a network of infected computers to launch a denial of service attack, Cluley said.

"We don't know anything yet about where it is coming from," Hypponen said. "It's fairly well made and hard to analyze with normal tools."

F-Secure had received many reports of the e-mail but few submissions of the virus itself, indicating that damage so far is limited. Cluely agreed: "I wouldn't classify this as one of the biggest viruses of the year, but that doesn't mean it isn't a threat" he said.

Detection of Win32. Grum by antivirus programs was "mediocre" on Thursday evening, according to Sunbelt Software Inc., and some big vendors were still not picking it up Friday morning, Hypponen said.

F-Secure and Sophos are blocking the virus and all major vendors are likely to do so soon, he said. Some e-mail filtering systems were also not blocking the virus on Friday morning.

The IDG News Service is a Network World affiliate.