Security experts have expressed serious concern about recently-discovered flaws in Internet Explorer that seem to be the focus of an insidious attack.
Many popular websites, including search engines and shopping sites, have been secretly hacked and have had mysterious code placed on their Web servers. When a user running Internet Explorer logs on to a contaminated site, the user's PC is infected with malicious code, which has the potential to cause further problems.
The exact nature of the problem is unclear, although experts within many of the world's top e-security firms, as well as the SANS Institute and the US Department of Homeland Security, have acknowledged that something is amiss.
Backdoors are opened on infected PCs and key-logging software is also installed, allowing the creators of the code to steal passwords, PIN numbers and credit card details. According to some analysts, the hackers behind the malware are actually loading computers with so-called "adware" or "spamware" software that can push unwanted ads to users or steal personal data for the purpose of spam emailing.
Of course there is always the possibility of an enormous Distributed Denial of Service (DDoS) attack, once enough computers are converted into zombies. But this is thought to be unlikely.
"This is what everyone has been really frightened about for a while now," said Conor Flynn, technical director with Rits Information Security in Dublin. The fear is rooted in the fact that there is no patch from Microsoft for the flaws, nor is there any indication that a patch is on the verge of being released. Though the virus-like infection rate remains low, experts like Flynn say the matter could become a more serious problem unless a fix is released soon. "There is no question that this one could be devastating," he said.
The perpetrators could be spammers, one of the few groups to have made money from hacking. They me from Eastern European or Russian-organised crime gangs, as the "high quality" code that infects websites redirects browsers to Russian-based Web servers.
For website proprietors, the best defence is to ensure that Web servers are fully patched and guarded against all attacks - particularly those running Internet Information Server (IIS), which seems to be a favourite of attackers due to previously-revealed vulnerabilities.
Home users, meanwhile, should shut down options like ActiveX on Internet Explorer, which is a mechanism used by malicious code to upload onto PCs. Or you could always switch to Opera, Safari, Netscape or Mozilla, Internet Explorer's rival browsers.
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