The cat’s out of the bag – DNS flaw details revealed

July 23, 2008

Information Security

On July 9th security researcher Dan Kaminsky announced a serious flaw in DNS. Dan had been working with vendors to address it, but he refused to share the details until Black Hat USA 2008 in August. But now the cat’s out of the bag. Halvar Flake took a stab at it, then Matsano Chargen accidentally posted <a href="full details about it, then Dan cryptically acknowledged it had been disclosed.
The flaw makes it possible to perform DNS cache poisoning attacks. DNS (Domain Name System) is analogous to a phone book. Your computer sends a hostname to a DNS server and it returns a numeric IP address, in the same way that you look up a name in a phone book to find out a phone number. If a DNS cache poisoning attack is performed successfully, your computer is returned an IP address that belongs to the attacker instead of the correct IP address.
This is serious since all Internet services (web, email, IM, etc.) rely on DNS. You could think you’re logging into Bank of America, but really be logging into the attacker’s website. Same with your email. Then the attacker would have your login credentials and any other information you entered.
If you manage a DNS server, patch it ASAP.
To check if the DNS server you use is vulnerable, visit DoxPara and click “Check My DNS”. If you’re checking from your home Internet connection, this is likely your ISP’s DNS server.

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