botnets
I am surprised how little attention this gets. There are hundreds of people making $10k+ per month with botnets. It doesn't even matter how good the hardware is when you have thousands of zombies. There are pre-made miners available for sale, some of which are completely undetectable. Once anti-virus detects them it is very easy to crypt them and carry on.
This is not a small scale thing. It is not an exception. This is happening on an absolutely massive scale and once people find out just how much of this is going on bitcoin is going to suffer, hard.
I'm not making this up. I'm not spreading FUD. This is a fact and it is my prediction that it will hit Bitcoin harder than anything else has done to date.
If you don't believe me just head over to some of the popular black hat forums and search for bitcoin.
Also, MMM.
That doesn't require a large number of nodes in Russia.
Still you aren't the first to bring up botnets, however the influence of botnets is small and waning. Each generation has made botnets less suitable for Bitcoin mining (CPU -> GPU -> FPGA -> ASIC). The average botnet node is a much older Windows XP box. While top of the line CPU can push 20MH/s significantly older CPU can't. For example an Athlon 64 X2 4000+ (an impressive CPU in its day) gets only 2MH/s and a 8 year old single core Celeron a fraction of a MH/s. So even a 100,000 node botnet @ 100% load 24/7 would be maybe 100GH/s. When you consider the average node may only be on 30% of the time and load needs to be throttled to avoid detection real world it might be more like 16 GH/s per 100,000 nodes. FPGA would have killed botnets eventually but ASICs will do it much faster. In 2013 difficulty will probably be 10x to 20x as high as now. That combined with the subsidy cut means revenue per GH/s is going to fall to pennies a day.
I would point out LiteCoin is particularly susceptible to botnets and while it can be mined with a GPU the ratio between CPU throughput and GPU throughput is relatively low thus it takes a smaller number of nodes to equal the entire hashing power of the LiteCoin network. As Bitcoin becomes increasingly toxic to botnet they will migrate to LiteCoin and represent a larger and large portion of hashing power.