If you wanna CPU mine, you gotta download a specific CPU miner.
Source: I mine Litecoins.
http://www.completefusion.com/profitable-litecoin-mining-on-...
A smarter criminal would have opted for g2.2xlarge instances as well as mining for a currently more profitable coin. Granted he'd need to be careful not to leave a trail, he could essentially trade these coins for LTC and still obtain more litecoins.
I'll boinc on my desktop for science and goodwill but will not waste any more time on Ripple's program or indeed on Ripple itself, as brilliant as the idea is. Ripple's founders are hanging on to their 60%+ outstanding Ripples so tightly that I suspect the project will never truly get off the ground.
As much as people criticize it, I think some variation of Bitcoin's seignorage mining is the only realistic way to bootstrap a successful virtual currency, at least at this point.
See https://www.multipool.us/ for reference. Although it fluctuates a lot, LTC has been around 4th-5th in profitability among scrypt coins. Often 5th. And wait for Doge to feature in these pools :-)
Then the GPU instances will be available in the list. Ran into the same thing myself ;)
A cc2.8xlarge is reported to mine at 85 kh/s, so 20 of them would give you 1700 kh/s. That's roughly equivalent to a couple of high-end AMD GPUs (say a couple of overclocked 290x). This hashing power gives you a little over 0.5 LTC per day. It mined for two days, so it gained a little over 1 LTC. Let's call it $40.
That's right, the idiot behind this cost the OP $3000+ for $40 profit. A smarter criminal would have spawn GPU instances on EC2.