There are currently known vulnerabilities with DNS servers across all implementations.  These vulnerabilities are not vendor specific, in fact all DNS distributions are vulnerable.  I recommend all organizations develop an action plan immediately to identify and patch all DNS servers, applications, and clients on all networks in your control.

These vulnerabilities expose vulnerable DNS servers to DNS cache poisoning, this potentially can effect proper email delivery and what website you actually visit when entering a URL into a browser.

DNS specifically calls for 16 bit transaction ID field, which would require 32,768 “guesses” to predict the ID.  Many implementations use a smaller number of bits, and thus would require considerably fewer guesses.

US-CERT has an excellent write up on this vulnerability here.

You can find patch specifics for Microsoft here.

If you are running BIND 8, there is currently no solution and no plans to fix this problem for this platform, it is highly recommended to immediately look at upgrading to BIND 9.

If you only apply one patch in 2008, this should be it!

If you are using DNS from your ISP, you may still be vulnerable!

To assist organizations in containing this issue, I put together a few actions steps to get everyone on track.

  1. Identify all DNS servers on your network and any networks you are responsible for.  To be sure, you may want to run a port scan for anything listening on UDP port 53.
  2. Identify vendors responsible for each and every DNS server found from step 1.
  3. Refer to US-Cert for links to each vendor to the appropriate patch documentation.
  4. Patch all Servers.
  5. Repeat for all DNS Clients, although these patches are more focused on DNS Servers.

It is highly recommended all servers be patched before the Black Hat convention on August 6th when more information will be disclosed.

UPDATE:

You can check your upstream DNS Servers here:
http://www.doxpara.com/

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Author: Christopher