Botnets Evolving to Mobile Devices

Botnets have tended to hide in the nooks and crevices of servers and endpoint devices. Now a growing number are hiding in the palms of users' hands. That's one of the conclusions of a new report detailing the evolving state of malicious bots.

"Mobile Bots: The Next Evolution of Bad Bots" examined requests from 100 million mobile devices on the Distil network from six major cellular carriers during a 45-day period. The company found that 5.8% of those devices hosted bots used to attack websites and apps – which works out to 5.8 million devices humming away with activity that their owners know nothing about.

"The volume was a surprise," says Edward Roberts, senior director of product marketing at Distil Networks. The research team even took another sampling run to verify the number, he says. In all, "one in 17 network requests was a bad bot request," Roberts says,

Another significant step in the evolution of these bots is their use. The "traditional" use of botnets is as an engine for distributed denial-of-service (DDoS) attacks or spam campaigns. These mobile bots, though, seem to be focused on a different sort of attack.

"It's an attack on the economy," Roberts says, describing the activity in which bots repeatedly scrape prices from a retail site so that a competitor can constantly match or undercut the price.

Another activity for these mobile bots is hunting through brand loyalty sites looking for login information so that premium products or "points" can be harvested for the botnet owner. A side effect of this type of activity is much lower traffic volume than that often seen in bot-infected devices.

"We only see an average of 50 requests a day from these devices," Roberts says. "The activity is low and slow and highly targeted." In this targeted activity, the nature of a cellular-connected device comes into play, as the IP address will change every time the device moves from one cell to another.

The one thing that hasn't evolved is the way in which the devices become infected, the report points out. Tried-and-true infection mechanisms, including malicious file attachments in email, infected files behind website links, and drive-by infections that use redirected links, are all commonly found. As with desktop and laptop computers, the researchers recommend anti-malware software and user education as primary defenses against infection and botnet recruitment.

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