Forget sneaky hackers and the jealous machinations of your rivals. The greatest threat to IT security, PC Advisor readers reckon, comes from within.

Nearly half (45.9 percent) of respondents to a recent PC Advisor website poll indicated they consider disgruntled insiders and ex-employees pose the greatest menace to the safety of a company’s IT setup.

"Almost every company has a few disgruntled employees — people who, for one reason or another, have a grudge against the company," said Peter Thomas, IT consultant at Datasolve and regular visitor to

"If they have access to the computer system, they can create havoc very quickly. The attack from within is far more difficult to stop, and potentially far more damaging. Internal subversion can go unnoticed for long periods, and the consequential loss could be huge," he said.

Second favourite in the culprit stakes was careless employees, which raked in more than a third of the votes (38.2 percent). Such sentiments were shared by PC Advisor reader Dan Parker.

“Ignorance must play a significant part in security problems,” said Mr Parker. "From minor stuff like using idiotly [sic] guessable passwords to lax internal security making it easy for outsiders to have access to screens and keyboards."

Despite the high-profile media coverage given to rogue worm attacks, viruses and DOS (denial of service) assaults, hackers garnered just 10.7 percent of the vote.

Meanwhile, fears about threats from rival companies trying to get one over on the opposition hardly registered at all, with a mere 3.3 percent expressing concern.