Poisoned web poses risk to security
COMPUTER criminals are coming up with ever stealthier ways to make money. Rather than attack PCs or email inboxes, their latest trick is to subvert the very infrastructure of the internet, the domain name system (DNS) that routes all net traffic.
In doing so, they redirect internet users to bogus websites, where visitors could have their passwords and credit details stolen, be forced to download malicious software, or be directed to links to pay-per-click adverts.
This kind of attack is called DNS cache poisoning or polluting. It was first done by pranksters in the early years of the internet, but it had limited impact and security patches eliminated the problem.
Now new loopholes have opened and poisoning appears to be back. This time experts can't be sure how much damage it might do. "We see the combination of DNS poisoning with other hostile actions as having a serious impact," says Swa Frantzen, a Belgium-based volunteer member of the SANS Internet Storm Center. "I think it's going to slowly die out," says Joe Stewart of net security company Lurhq in Chicago.
Internet poisoning returned to the fore in early March, when DNS software provided by antivirus firm Symantec was found to have a bug that made poisoning possible. Weeks later, the SANS centre uncovered a second spate of poisonings, but this time it was due to a security loophole.
Companies can protect themselves by switching to BIND 9, which will not accept or pass on poisoned information. But Gerhard Eschelbeck of the internet security company Qualys in Redwood Shores, California, says the problem may not be over. "I would not rule anything out. There are other creative ways that attackers can find to poison the DNS," he says. And poisoning is a much bigger deal than it was in the early days, because hackers can now use the technique to introduce "malware" onto servers and PCs, says Frantzen.