The Immutable Friday Fav Five for September 16, 2011

Here are the five or more links that I found interesting for this week:

  • Dave Hoelzer from SANS provides some very useful “AuditCasts.” These are short, instructional videos on various topics. This week, Dave talked about the benefits of split DNS. One implementation of split DNS that Dave did not mention specifically is to not have the internal DNS servers forward requests at all; rather, you may rely on your proxy to do the queries for you. This can be helpful if a malware infection is trying to phone home. If they are relying on DNS for the call-back, it might fail.
  • What should you do after compromising a system (on which you had permission, of course)? These Linux and Windows community docs provide some good tips. I wouldn’t recommend running these commands or tools without knowing exactly what the outcome will be. They could be dangerous.
  • The Morto RDP worm takes advantage of poorly chosen passwords. Microsoft has a pretty good write-up of the behavior of the worm. OSSEC should detect the invalid logon attempts. I have some ideas on how a few rules could detect this general class of infection.
  • Barracuda, the company that has a pretty decent anti-spam gateway, offers their RBL for free. I have been using the Spamhaus Zen RBL for quite some time and decided to give this a try. Putting it before the Spamhaus list, the result has been pretty good. Spamhaus now rejects only 3-5 messages a day since the BRBL is blocking lots of spam that Spamhaus would have caught. So far, I know of no false-positives. Using both seems to work pretty well.
  • Lenny Zeltser reminds us that security is best designed with failure in mind. Security controls will fail, but that doesn’t necessarily have to lead to an information breach. A good security design plans on these controls failing with the information remaining safe.

That’s it for today. Have a great weekend!

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