A Linux-based Trojan, which security experts believe may have originated in the UK, has been spotted on the Net.

Remote Shell is similar to Back Orifice on the Windows platform according to vulnerability assessment services firm Qualys.

According to Qualys, the trojan is similar to Back Orifice on the Windows platform and in a a doom-laden alert,suggests Remote Shell "could eclipse Code Red" in its impact.

We think this apocalyptic scenario is highly unlikely. And so do many antivirus experts.

Eric Chien, chief researcher at Symantec's antivirus research centre, does not expect the virus to spread, principally because it lacks the self-replication characteristics that made Code Red and the Lion worm (which affected Linux servers) such nuisances.

"I don't think anyone in the security business would consider this particular Linux virus a major (or even minor?) threat to real world computer users," said Chien. "However, it does reiterate the fact that Linux is susceptible just like any other operating system."

Only a handful of viruses has ever been known to infect Linux systems against the many thousands which infect Windows machines.

That said users may wish to consider using Qualys' free vulnerability test (registration required). Antivirus vendors are in the process of updating their signature definition files to detect the Trojan.

Qualys suggests Remote Shell can be disseminated by inconspicuous emails and replicates itself on the infected Linux-based system. The Trojan installs a backdoor that listens for incoming connections on UDP port 5503 or higher, enabling remote attackers to connect and take control of the system.

Once a system is infected, the Remote Shell Trojan calls home to a UK-based Web site where hackers may accumulate lists of infected systems. Qualys has informed the UK's National Criminal Intelligence Service and the FBI about the Trojan and we understand the police are investigating its origins. ®

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