According to a 3-month study of 600 botnets which have infiltrated enterprise networks, bot infections are on the rise in the corporate environment. The research, done by Damballa, indicates that it is small botnets, not large ones, that are the most prevalent in the enterprise environment.
As you can see from the graph above, 57% of the botnets infecting enterprises are considered "small", which is defined as a botnet with 1-100 active members. However, despite being less well-known, these botnets are potentially more dangerous:
While many people focus on the biggest botnets circulating around the Internet, it appears that the smaller botnets are not only more prevalent within real-life enterprise environments, but that they’re also doing different things. And, in most cases, those “different things” are more dangerous since they’re more specific to the enterprise environment they’re operating within.
The study indicates that many of these small botnets have been created with low-cost or free DIY kits that can be downloaded from the Internet. In most cases, these small botnets are described as "highly-targeted at particular enterprises", sometimes requiring a degree of familiarity of the breached enterprise. This could indicate an insider threat issue that we previously haven't seen or talked about. The target data in these small botnets is often professionally managed with financial controller authentication details (for money transfers), customer database and source code being the top targets.
The problem with these small botnets, aside from their very targeted attacks, is that they often evade detection. Though they are small, these botnets are very dangerous! Damballa puts out a product to detect botnets, but I know very little about it. You can do some independent research on your own to determine how your enterprise will try to detect such intrusions.
Via dark reading