UNDERGROUND

that, by controlling NIC, you could make any computer on the Net 'pose' as a machine trusted by a computer you might want to hack. Security often depended on a computer's name, and NIC effectively controlled that name.

When Prime Suspect managed to get inside NIC's sister system, he told Mendax and gave him access to the computer. Each hacker then began his own attack on NIC. When Mendax finally got root on NIC, the power was intoxicating. Prime Suspect got root at the same time but using a different method. They were both in.

Inside NIC, Mendax began by inserting a backdoor – a method of getting back into the computer at a later date in case an admin repaired the security flaws the hackers had used to get into the machine. From now on, if he telnetted into the system's Data Defense Network (DDN) information server and typed 'login 0' he would have instant, invisible root access to NIC.

That step completed, he looked around for interesting things to read. One file held what appeared to be a list of satellite and microwave dish coordinates – longitude, latitudes, transponder frequencies. Such coordinates might in theory allow someone to build a complete map of communications devices which were used to move the DOD's computer data around the world.

Mendax also penetrated MILNET's Security Coordination Center, which collected reports on every possible security incident on a MILNET computer. Those computers – largely TOPS-20s made by DEC – contained good automatic security programs. Any number of out-of-the-ordinary events would trigger an automatic security report. Someone logging into a machine for too long. A large number of failed login attempts, suggesting password guessing. Two people logging into the same account at the same time. Alarm bells would go off and the local computer would immediately send a security viola- tion report to the MILNET security centre, where it would be added to the 'hot list'.

Mendax flipped through page after page of MILNET's security reports on his screen. Most looked like nothing –