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Boosting Your Defenses Against Botnet Infections

In the past few weeks since the Google/China incident, we have seen a number of interesting blog posts and white papers that provide further details on some of the techniques used by the attackers.
In the past few weeks since the Google/China incident, we have seen a number of interesting blog posts and white papers that provide further details on some of the techniques used by the attackers.

These articles also show the pervasiveness of these type of security incidents. For example, Damballa has published data that shows botnets have hundreds of thousands of members in enterprise networks, and that most enterprise networks have multiple botnets operating within them. Botnets based on "Zeus" are very common, and NetWitness recently published a detailed analysis of one such Zeus based botnet called "Kneber," which has a membership of more than 74,000 PCs -- reaching into more than 2,000 global and 350 U.S.-based entities -- within all commercial and government sectors. Brian Krebs has been covering these botnets for years, first while he was at The Washington Post, and now on his own where he has many excellent examples of the reach and damage of botnets. In November 2009 the Computer Security Group at UCSB published an impressive report on the Torpig botnet, where they managed to take over the command and control server. During the 10 days they were botmaster, they observed 180,000 infected machines sending data.

The malware used in the setup and operation of these botnets changes frequently and is engineered to circumvent the protection provided by the typical antivirus systems. Still there are ways to protect your organization against the most frequent attacks:
  • User awareness: The vast majority of botnet malware counts on user assistance to become entrenched. Make your users aware of the threats, and help them to become conscious of the threats in their interactions on social networks and when downloading and installing software.
  • Software infrastructure: A large part of the malware installs itself by exploiting known vulnerabilities in the operating system and applications installed on the user's computer. Work on keeping your infrastructure consistently updated and keep track of all software installed on users' desktops.
  • Network monitoring: Outbound network monitoring provides the means to track down infected desktops and to take them off the network.

Increasing your efficiencies in these three areas will significantly improve your organization's resilience against the common mass infections techniques many of the major botnet operators are using.

-- As the CTO for Qualys, Wolfgang Kandek is responsible for product direction and all operational aspects of the QualysGuard platform and its infrastructure. Wolfgang has more than 20 years of experience in developing and managing information systems. His focus has been on Unix-based server architectures and application delivery through the Internet. Wolfgang provides the latest commentary on his blog: laws.qualys.com and also publishes his Patch Tuesday commentary to the QualysGuard channel: www.youtube.com/QualysGuard. He is a frequent source in business and trade media and speaks at industry conferences around the world, most recently at RSA 2009.

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