The four-man group, called Last Stage of Delerium, successfully broke into the Web server, in a competition designed to demonstrate the strength of security specialist Argus' Pit Bull intrusion prevention software.
Although the successful hack at the Infosec show at London's Olympia will prove embarrassing to Argus, the company said the problem lies in the Solaris operating system running on X86 hardware.
The hackers managed to penetrate the server after identifying an unpublished vulnerability in Solaris.
The group is the first to crack into the server even though Argus has hosted similar competitions around the world, one of which attracted more than five million unsuccessful hacking attempts.
Argus chief executive Randy Sandone said the group had highlighted the need for IT departments to check the security of their operating systems. "No single product, group of products, or set of security services can completely eliminate system vulnerabilities," he said.