The worm appears with the subject line: "Tsunami donation! Please help!" and invites recipients to open an attachment called "tsunami.exe" -- which, if opened, will forward the virus to other Internet users.

It could also initiate a denial-of-service attack against a German hacking Web Site, Sophos said, in which the site's server would be bombarded with messages, putting it out of action.

"Duping innocent users into believing that they may be helping the tsunami disaster aid efforts shows hackers stooping to a new low," Sophos senior technology consultant Graham Cluley said in a statement.