(click image for larger view) Slideshow: 10 Massive Security BreachesAre you prepared to stop attacks by malicious insiders or a former employee? On Tuesday, Jason Cornish, 37, plead guilty in federal court to executing an attack against his former employer, pharmaceutical firm Shionogi.

Based in Japan, Shionogi also operates in New Jersey, as well as Georgia, where Cornish had worked as an IT employee before resigning in September 2010. But in February 2011, Cornish accessed the corporate network and began deleting virtual servers, in retribution for layoffs that affected a close friend and former colleague.

As a result of those attacks, which cost Shionogi an estimated $800,000 in losses after responding to the attack and restoring its systems, Cornish--due to be sentenced in November--faces up to 10 years in prison and a $250,000 fine. But security experts said Shionogi is also at fault, because of its apparently ineffective security environment and disaster recovery strategy.

Here's how businesses can do better:

Route All Offsite Access Through A VPN

Ultimately, the FBI's Cyber Crimes Task Force traced the attack against Shionogi to a free Wi-Fi connection at a McDonald's, and found that Cornish had made a $4.96 credit card purchase there just minutes before the attack. But FBI investigators also found that he'd accessed the corporate infrastructure multiple times from his home network. That means Shionogi had failed to spot suspicious activity, especially ...