For example, bugs in web browsers have allowed hackers to gain access to company systems.

Those security holes could allow malicious hackers to use the Apple Developer Connection in phishing attacks to gain access to users' login and password information.

This feature aims to mitigate problems whereby newly-discovered flaws in the browser (or in ActiveX controls hosted inside it) allowed hackers to subversively install software on the user's computer (typically spyware).

C8 America Online said that it would take steps to fix flaws in its network that allowed hackers to access personal information about some members last week.

Critics point to the fact that data held on systems like this could potentially allow hackers to work out when your are most likely to be away from home, leaving it vulnerable to thieves.

More than 100,000 Apple iPad users have had their data revealed, thanks to a Web site glitch that allowed hackers to take the information, according to Ryan Tate at Gawker.

These criminals posted promises of early previews and access to the site, which led people to unintentionally buy malicious software and allowed hackers to gain access to their accounts.

Others are used to open "trap doors" in a computer system, allowing outside hackers to gain secret information or otherwise exploit the system.

Algorithmic flaws at one time allowed hackers to produce fraudulent certificates, though CAs have responded by no longer using the affected algorithms.

The problem allowed hackers to design Web sites and e-mail messages that caused users to unknowingly download dangerous programs and "run code of the attacker's choice," as the company's security bulletin put it.