The worm is largely benign and does not damage data on the infected PC, but the flurry of e-mails its sends to other computers could swamp a business' network, said Ian Hameroff, business manager for security solutions at antivirus and PC services company Computer Associates.
"It is spreading at a medium rate, nowhere near epidemic," he said. "The interesting thing is its usage as a vehicle for a political message."
Rival antivirus firm Trend Micro rated the virus as a medium threat.
The mass-mailing worm represents the latest strike in the online battle between supporters of the Palestinians and those of the Israelis. Late last year, both sides traded blows by defacing Web sites that support the opposing side.
Though other political viruses have been seen in the past, Injustice has the potential to be the most effective to date.
The virus appears as an attachment to an e-mail message with the subject line "RE: Injustice" and the following message:
Dear (Outlook User name)/ Did you send the attached message, I was not expecting this from you!
The worm is a Visual Basic script attachment called INJUSTICE.TXT.VBS. Once opened, the program will display an anti-Israeli message in a text dialog box.
"PLEASE ACCEPT MY APOLOGIES FOR DISTURBING YOU," states the message. "Remember that one day YOU may be in this situation. We need every possible help." The rest of the message describes the death of a 12-year-old Palestinian boy.
The virus sends itself in e-mail messages to the first 50 entries in the infected computer's Outlook address book, along with 18 Israeli government addresses, eight organizations and to the Webmaster of the country's official Web site.
Finally, Injustice uses Microsoft's Internet Explorer to open six windows to a variety of Web sites, including an electronic petition to the United Nations High Commissioner for Human Rights.
"I've had people send me e-mail to get me to sign a petition," said Susan Orbuch, spokeswoman for Trend Micro. "But I've never seen a virus that tries to get people to sign a petition."
Trend Micro calls the virus VBS_Staple.A.
The virus writer apparently tried to make the virus as harmless as possible.
"Note: Do not worry," he states in the text of the virus. "This is a harmless virus. It will not do any thing to your system. The intension (sic) is to help Palestinian people to live in PEASE (sic) in their own land."