Fizzer stealth worm spreads via KaZaA

Dangerous payload

Yet another Internet worm has been discovered spreading through the KaZaA P2P file-sharing network.

Fizzer, which can spread via email as well as over file sharing networks, is more dangerous that most such worms because its malicious code includes key logging and Trojan functionality.

The worm normally arrives at the target computers as an executable file and activates when a user launches it.

Russian AV firm Kaspersky Labs said today that it has received confirmed reports of infections by Fizzer. However indications are that the spread of the worm is modest, at worst.

So there's no need to panic.

To spread via email, Fizzer scans the addresses in a victim's Outlook and Windows address books or it randomly attacks email addresses in public email systems such as hotmail.com and yahoo.com. Next, the worm, in the name of the computer owner, clandestinely sends out infected messages using different subjects, message texts and file attachment names.

To spread via KaZaA, Fizzer creates multiple copies of itself under random names, and places these files in the victim computer's dedicated KaZaA file-sharing folder. By doing so, Fizzer becomes "available" to all other network participants.

Fizzer carries a dangerous payload that can cause confidential data to be leaked from infected computers. The worm installs a keyboard-logging program that intercepts and records all keyboard strokes in a separate log file. To transmit this information, Fizzer loads a backdoor utility that allows crackers/VXers to control a computer via IRC channels.

Additionally, the worm regularly connects with Web page located on the Geocities server from which it attempts to download updated version of its executable modules.

In an attempt to foil detection, Fizzer also attempts to shut down an array of widely used anti-virus programs that might be running on a victim's PC.

A write-up of the worm by Kasperky gives more information.

To avoid infection users are advised to apply standard precautions. Avoid open unsolicited attachments, even when they appear to come from people you trust, and update AV tools to detect the worm. AV vendors are in the process of updating signature definitions to recognise Fizzer.

It's still possible to remove the worm if you get infected but prevention is far easier than cure.

Using P2P networks as a vector for viral propagation has become a popular trick of late.

In February, the Igloo worm (which falsely promised racy pictures of celebrity nudes) spread through KaZaA. In August 2002, the Duload worm used attempted similar propagation tactics.

Before that we had the (awkwardly named) Backdoor.K0wbot.1.3.B and Benjamin worm.

So Fizzer is just the latest in a long and ignoble line. However its use of random names and payload makes it more stealthy and dangerous than most of its predecessors. ®

Related Stories

Madonna's borderline MP3 tactics
P2P virus fakes nude Zeta Jones pics
Worm spreads through KaZaA network, again
Altnet wakes up as worm spreads through KaZaA

Sponsored: Network DDoS protection