Security company warns of Hotmail worm

Security company Finjan Software has warned of a security vulnerability in Microsoft's Hotmail Web-based email service, but Microsoft said that the security hole has already been closed.

The new security flaw, known as a cross-site scripting vulnerability, could be used to create an Internet worm that steals email addresses from Hotmail users' accounts, captures credit card numbers or installs Trojan horse programs, Finjan said. The vulnerability exists in the way that Hotmail treats e-mail containing ActiveX controls, which are small, portable pieces of software code that enable programmers to embed sophisticated user interface elements into Web pages for use over a corporate intranet or the Internet. Hotmail content filters do not adequately block email messages containing the controls, Finjan said.

In cross-site scripting attacks, malicious hackers embed attack code in Web pages or HTML (Hypertext Markup Language) email messages. Once executed, cross-site scripting attacks can give attackers access to personal account or financial information or control over a remote machine.

As a result of the Hotmail vulnerability, attackers could run malicious code on the computer of a Hotmail user who opened an email containing the malicious ActiveX control, Finjan said.

By embedding a worm engine in the email and code that would grab the addresses from the Hotmail user's address books, attackers could use the Hotmail vulnerability to make a worm, Finjan said.

A Microsoft spokesman said the company was informed of the problem by Finjan on September 8 and patched the company's Hotmail systems within 24 hours.

No Hotmail users were affected by the cross-site scripting vulnerability, which no longer affects Hotmail users, he said.

Microsoft has faced frequent criticism for security holes in its Hotmail and .NET Passport single sign-on service, which are used by millions of people on the Internet. In July, for example, the company issued an emergency patch for the .NET Passport service after security researchers discovered and publicised a hole in a feature that helps users update their account password.

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.

Paul Roberts

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Cate Bacon

Aruba Instant On AP11D

The strength of the Aruba Instant On AP11D is that the design and feature set support the modern, flexible, and mobile way of working.

Dr Prabigya Shiwakoti

Aruba Instant On AP11D

Aruba backs the AP11D up with a two-year warranty and 24/7 phone support.

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers


This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang


It really doesn’t get more “gaming laptop” than this.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?