SAN FRANCISCO, Nov 28: A spy computer worm that tracks keystrokes to potentially steal passwords and other secret information spread rapidly across the Internet on Monday, computer security companies warned.

The worm, called Badtrans, spreads through Microsoft e-mail programs like Outlook or Outlook Express by automatically sending itself to unanswered e-mails in inboxes.

“It does no damage to files but does drop a backdoor trojan on the machine, which would allow a hacker to come back and access personal information,” said April Goostree, virus research manager at McAfee.com.

It is particularly hard to spot because its subject line varies widely, often assuming the text of the unanswered e-mail whose e-mail address it adopts.

The name of the attachments varies as well, with suffixes including .doc, .pics and .news. The attachment containing the virus can be activated simply by reading or previewing the e-mail, and doesn’t need to be double clicked or opened separately.

According to computer experts, the worm contains a keystroke logger that can be used to record what people type to obtain passwords and credit card numbers.

The worm has already been spotted in at least 50 countries, with Germany, the United Kingdom and the United States hardest hit.

JAIL INMATES: Inmates of Tihar jail in New Delhi could soon be surfing on the internet, working on MS Office and many other programmes, reports said on Tuesday.