Trojan.Ramvicrype uses the RC4 algorithm to encrypt files on systems running Windows 98, 95, XP, Windows Me, Vista, NT, Windows Server 2003 and Windows 2000, according to Symantec's Web site.
Computers with files that have the .vicrypt extension are infected, a Symantec researcher wrote in a blog post this weekend.
A Web search for "vicrypt help" brings up a news release for a company called Exquisys Software Technology Ltd in Mauritius offering a product called Antivicrypt that will "repair and restore" files that are "damaged." Symantec reports that the company charges for the product.
For more, read New Trojan encrypts files but leaves no ransom note from CNET News.