Windows hit by zero-day flaw

Unpatched bug in the XMLHTTP 4.0 ActiveX control being exploited on malicious sites

The U.S. Department of Homeland Security has warned that attackers are exploiting an unpatched flaw in Windows to compromise systems via malicious websites.

Microsoft on Friday said it was investigating reports of a newly discovered, unpatched bug in the XMLHTTP 4.0 ActiveX control, which it confirmed was being exploited on malicious sites. The bug has the potential to infect a large number of systems. Since it doesn't require any user interaction, a user must merely use Internet Explorer to visit a site containing the exploit.

Microsoft said it is determining whether the flaw requires an out-of-cycle patch. The company acknowledged that it could be used to spread malicious code via banner ads or via legitimate sites that have been compromised, as has happened in the past.

The ActiveX control in question is part of part of Microsoft XML Core Services, which is used to build XML-based web applications. All versions of Windows 2000, 2003 and XP are affected, according to Secunia, which gave the bug its most severe rating, "extremely critical." Because it isn't a browser flaw, the bug can be exploited via any version of Explorer, including the newly released, security-conscious IE 7. Windows Server 2003 users are less likely to be affected since that OS runs Explorer in a locked-down mode that disables ActiveX by default.

Microsoft didn't specify the flaw in XMLHTTP, but said it gives an attacker the same privileges as the logged-in user. Until a patch is available Microsoft said users can protect themselves by adjusting security restrictions or setting the kill-bit for the affected ActiveX control, among other workarounds.

Join the newsletter!


Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Matthew Broersma
Show Comments

Brand Post

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Cathy Giles

Brother MFC-L8900CDW

The Brother MFC-L8900CDW is an absolute stand out. I struggle to fault it.

Luke Hill


I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?