An exploit has been published which targets an unpatched flaw in Internet Explorer (IE) 6 and 7.
Security firm Symantec tested the exploit and confirmed that it did work, though it was unreliable. However its analysis team said that they expected a fully-functional exploit to work in the near future.
If this exploit is used, attackers will be able to insert the exploit into websites. If an IE6 or IE7 user does browse one of these sites with Javascript enabled, they will be infected and their computer compromised.
The exploit targets a flaw in the way IE uses cascading style sheets (CSS), which is used to define the presentation of a website's content.
Symantec advised Internet Explorer users to ensure their antivirus was up to date, disable JavaScript and only visit websites they trusted until a fix was available.
IT PRO has contacted Microsoft for comment, but the company had not responded at the time of publication.
There have been no reports of any exploits in the wild, but IT PRO blogger Davey Winder said that this could all change as hackers look to rush out attacks before security vendors have updated signatures to find the exploit.
He said: "Microsoft, will, I imagine, be reactive rather than proactive with a patch only being prioritised after such attacks become widespread."
In August, Microsoft defended its ongoing use of Internet Explorer 6, which still has a quarter of web users, claiming that it was a matter of personal choice.
However, it did admit that as engineers, it wanted to see people upgrading to the latest versions.
