Researchers at Sophos said the worm, identified as W32/Crowt-A, takes its subject lines and message content from headlines gathered in real-time from Time Warners CNN Web site. The worms subject line and attachment share the same name, but continually change to mirror the front-page headline on the CNN site.
Once executed, Crowt-A installs a backdoor Trojan function that attempts to log keystrokes on infected PCs and sends gathered data to a remote user. Sophos warned that Trojans are often used by malicious hackers to hijack personal information such as bank passwords, Social Security numbers and credit card data.
The worm also attempts to send itself to e-mail addresses found on the infected computer.
To trick users into executing the file, the message text lifts legitimate news information direct from CNNs site. "Virus writers are always looking for new tricks to entice innocent computer users into running their malicious code; this latest ploy feeds on peoples desire for the latest news," said Sophos security consultant Carole Theriault.
Theriault said virus writers are preying on the reality that many e-mail users subscribe to legitimate news updates, but she warned that enterprises should make sure their anti-virus detection is constantly updated. "Users need to be suspicious of all unsolicited e-mail, whether its promising celebrity pictures or news updates."
Crowt-A copies itself to the SERVICES.EXE file in the Windows startup, templates and common program files folders, making the Windows startup folder a hidden folder at the same time. It sets entries in the registry at several locations to run the copies of itself on system startup, according to the Sophos alert.
The backdoor component connects by default on port 80 to a preprogrammed Web site and listens for instructions from a remote user. These instructions include changing the configuration-related registry setting, sending information about the infected computer, sending the users Windows address book, downloading files from remote locations, deleting files, rebooting the infected computer and setting up a command prompt that the remote user can control.
An infected machine can also be hijacked to act as a proxy server, to delete files from the Windows cookie folder and send virus-laden e-mails. "Some of these actions take place even without prompting from a remote user," Sophos added.
Data gathered by the keystroke logger is automatically sent to a Yahoo e-mail address or to the remote user via the backdoor.