redsoxh8r notes a blog post describing in some detail the operation of "man in the browser" Trojans used to empty victims' bank accounts. "Banker trojans have become a serious problem, especially in South America and the US. Trojans like Zeus, URLZone and others are the tip of the iceberg. These toolkits are now standard-issue weapons for criminals and state-sponsored hackers. Like Zeus, URLZone was created using a toolkit (available in underground markets). What this means is that the buyer of this toolkit can then create customized malware or botnets with different command-and-controls and configurations (such as which banks to attack), but having all the flexibility and power of the original toolkit. Having such a toolkit in the hands of multiple criminal groups paints a scary picture. It's simply not enough to eliminate a particular botnet and criminal group to solve this problem."