The latest variant of SDBot spreads through America Online instant messaging software (AIM) and installs surreptitious remote control software on victims' computers, focusing the media on security experts' concerns that instant messaging will become the next popular vector for these programs.

The program - known as W32.Loxbot.B - infects systems after a victim clicks on a link that seemingly comes from an acquaintance listed on the victim's AIM buddy list. The software downloads and installs remote administration software and connects back to one of two IRC servers to await further commands. The added load on the operating system can slow a computer's response time significantly, according to security firms' technical advisories. The bot is a modified version of another self-spreading program known as W32/SDBot.ADD and W32.Loxbot.A that also uses AIM to infect trusting victims.

Since the Nimda worm, security professionals have believed its only a matter of time before some bot variant can spread automatically through an instant messaging application. Taking those fears over the recent infections even farther, technical publication eWeek questions in an article headline "Is IM Doomed?"

Instant messaging applications certainly have their share of security issues, and rootkit technology - such as that contained in Loxbot.A - is also improving , with some of the newer types being nearly undetectable by currently deployed security software.

Yet, computer users historically have been able to defend themselves against these threats, through education, updates and a healthy dose of skepticism, and software developers have been able to patch flaws quickly. Simple defenses and the application's popularity mean that instant messaging users are unlikely to give the application up any time soon.

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