Botnet busts more for stunts than security, expert says
Microsoft and Symantec made headlines in September and in the summer by taking down major botnets. Now, one expert calls their actions ineffective, and wonders if the only reason they happened was to garner good press.
Working backwards, Symantec announced in September that they used a vulnerability within the ZeroAccess botnet's code to take down a significant part of it. Their actions gained headlines, because ZeroAccess has existed since 2010, and had a foothold on millions of systems globally.
In a similar situation, Microsoft took out 88 percent of the Citadel botnet this summer, going to far as to send configuration files to the infected systems that forced them to connect to sinkholes, removing them from criminal control. At the time, Microsoft said that 40 percent of the computers that were part of the operation were cleaned of infection.
However, there were those that said Microsoft's actions were nothing more than a clever PR stunt, and that they had no real impact on the threat landscape.
In a recent blog post, Damballa's CTO, Brian Foster, says that botnet takedowns often don't meet their stated goals of reducing the risk of infection online. In fact, he says, it's something else entirely.
"It makes me wonder if these efforts are for the sole purpose of garnering press, because they certainly don't have any lasting impact on end user safety," Foster wrote.
Supporting his theories, Foster listed three reasons that botnet takedowns are ineffective. To start, he noted, most takedowns are done haphazardly. In most cases, only a small percentage of the command and control servers for a given botnet ware grabbed by the do-gooders. Thus, while it makes good coverage to show that 24 percent of a botnet has been taken offline, "[it] still leaves 76 percent of it active. The attacker still has a strong foothold and can easily recover."
Further, takedowns do not account for secondary communication methods such as P2P channels, or domain generation algorithms (DGA) that may be used by malware.
"We looked at 43 pieces of malware and discovered that three of them had secondary callback methods. This means that for at least three of the botnets, security researchers need to take additional steps to make sure the botnet is disabled," Foster said.
Finally, he noted, the takedowns themselves do not result in the arrest of the person(s) behind the botnet itself. Unless the attacker has been arrested, it doesn't prevent them from starting anew and building a different botnet.
"Bottom line: If security researchers and their organizations are doing takedowns for marketing reasons, then it doesnt matter how they go about it. But if they are doing takedowns to truly limit Internet abuse and protect end users, then there needs to be a more thoughtful approach than what has typically been used by the industry. Otherwise, the bots will once again veer their ugly heads," Foster concluded.