A long ignored security hole in Microsoft's Internet Explorer is proving to be a goldmine for hackers, providing an easy way for them to plant malicious programs on vulnerable machines through hacker websites and instant messaging applications, security experts warn.
New attacks using the vulnerability include a worm that spreads through America Online's Instant Messenger (AIM) and a malicious website that silently loads snooping software on victims' machines, according to independent security expert Richard Smith.
Microsoft did not immediately respond to requests for comment.
The security hole, known as the "Object Data vulnerability," is in software code used by IE to process HTML (Hypertext Markup Language) pages containing an element called the Object Data tag. When properly exploited, the vulnerability enables an attacker to place a malicious computer program on a user's machine. No user actions are required to infect a machine, aside from opening an email message or visiting a web page rigged by an attacker.
Microsoft issued a software patch, MS03-032, on August 20 that was supposed to fix the problem. However, that patch failed to close the hole on Windows machines running Internet Explorer (IE) versions 5.01, 5.5 and 6.0.
On September 8, Microsoft acknowledged problems with the MS03-032 patch and promised to issue a fix as soon as possible. Since that time, no changes have been made to the MS03-032 patch. In the succeeding weeks, hackers moved quickly to take advantage of Redmond's slow response.
Recent exploits of the Object Data vulnerability include a virus that spreads over the AIM network, stealing users' account names and passwords then mailing links to a malicious hacker website to the victim's AIM correspondents (or "buddies"), Smith says.
Although the website associated with that threat has been removed, users who received and clicked on an infected instant message could have had their AIM account hijacked, according to Smith.
The vulnerability also cropped up in an email message containing HTML code that exploits the vulnerability. When opened, the message installs a file called "surferbar.dll" on to the victim's computer with links to pornographic websites, according to security company Secunia Ltd. of Copenhagen, Denmark.
While some of the new attacks are targeting holes in the MS3-032 patch, others may just be targeting users who have not applied the patch at all, Smith says. Short of issuing an updated patch that closed the hole, Microsoft should at least update its bulletin with a widely known workaround that closes the security hole, Smith says.
That fix, developed by a researcher at eEye Digital Security requires a small change to the Windows configuration that does not appear to affect any Windows features, but would protect users from attack, he says.
In the meantime, hackers will continue to take advantage of the Object Data vulnerability, which is easy to exploit and powerful, he says. "The sky's the limit of what you can do with (the Object Data vulnerability). This exploit is going to be used for years," Smith says.