Torpig, also known as Anserin or Sinowal is a type of botnet spread through systems compromised by the Mebroot rootkit by a variety of trojan horses for the purpose of collecting sensitive personal and corporate data such as bank account and credit card information.
Torpig circumvents antivirus software through the use of rootkit technology and scans the infected system for credentials, accounts and passwords as well as potentially allowing attackers full access to the computer.
By November 2008, it was estimated that Torpig had stolen the details of about 500,000 online bank accounts and credit and debit cards and was described as "one of the most advanced pieces of crimeware ever created".
[1] Torpig reportedly began development in 2005, evolving from that point to more effectively evade detection by the host system and antivirus software.
During that time, they extracted an unprecedented amount (over 70 GB) of stolen data and redirected 1.2 million IPs on to their private command and control server.