New security flaws have been discovered in Internet Explorer that could compromise users’ systems and allow hackers to bypass the added Windows XP security that came with SP2.

The latest alerts, discovered by http-equiv, concern Microsoft Internet Explorer 6.0. The first is a flaw in Explorer’s "drag and drop" feature, which could enable hackers to plant fake dialog boxes in a browser window.

The second concerns Explorer’s security zone restriction feature. Hackers could potentially bypass the security built into this feature in XP Service Pack 2. Once the security is bypassed, it is possible for hackers to plant malicious code on the victim’s computer, which could be used to execute local HTML documents. The two vulnerabilities, when used together, could allow malicious websites to plant and run code on a victim’s PC.

Users are vulnerable to both vulnerabilities unless they disable Active Scripting, said Thomas Kristensen, chief technology officer with Secunia. "These vulnerabilities are serious flaws in Internet Explorer," he said. "They do need to be fixed, but to put it in perspective, you’re not going to find your whole system is compromised by them."

The latest announcement follows a week of security warnings for Internet users. In recent days, flaws have been discovered in a number of popular web browsers, including Mozilla, Konquerer and Opera.

Those warnings concerned the tabbed browser features used in Opera, Mozilla and some add-ons to Internet Explorer. If users simultaneously opened secure and insecure websites using the tabbed browser feature, it was possible for a malicious website to plant content on the secure website in another tab. Users can protect themselves by disabling JavaScript when using the tabbed browser feature, or simply avoid using trusted and untrusted websites simultaneously.

Microsoft said in a statement that it didn’t know of any customers who had been attacked as a result of the security flaw. "Early reports indicate that significant user action is required to execute this attack," said the company, in a statement. "An attacker would need to first entice the user to visit a specific website and then entice the user to take a series of specific actions on the site, then reboot or log off before the attack could succeed."

While that makes the mass exploitation of these holes less likely, they nevertheless stand out as clear indication that problems with Microsoft software security are still far from solved with SP2.