The PE_MARI.A worm, previously reported by ZDNet, attempts to increase support for the legalisation of marijuana.
"It's very rare that a virus comes out into the wild and spreads quickly, Trend Micro's Andy Liou said. "This one probably wasn't attractive enough for people to spread."
Like pornographic emails, people might think it could reflect badly on them for others to know they have that kind of mail, according to Liou. "We're in a very serious situation now as virus writers are no longer an exceptional realm of highly technical people."
"Anyone with a motivation can write a virus," Liou said, adding that this virus writer's motivation was obviously political.
The virus was first discovered in the US in June. It arrives as an email with the message, "check this out" and carries an attached file -- SYSTEM32.EXE.
When activated the worm sends itself to everyone in your address book, appears as a little marijuana leaf in your system tray or on your taskbar and modifies the home pages of your Internet Explorer browser to point to my.marijuana.com.
When the marijuana leaf is clicked on, a message in support of legalising Marijuana pops up. The virus also appears twice a day as a message box reminder saying: "Time to toke up :)".
Although this worm hasn't been as prolific as the writer would have intended, in the next year worms will evolve into a greater threat, ZDNet reported. "They are adaptive; they are evolving," said Jose Nazario, a researcher for computer-security group.
"Worms, as they stand currently, are highly visible and easily blocked because of the high traffic they generate," Nazario said. But that will change in the next 12 to 18 months, he added.