Coreflood is a

trojan horse The Trojan Horse was a wooden horse said to have been used by the Greeks during the Trojan War to enter the city of Troy and win the war. The Trojan Horse is not mentioned in Homer's ''Iliad'', with the poem ending before the war is concluded, ...

and

botnet A botnet is a group of Internet-connected devices, each of which runs one or more bots. Botnets can be used to perform Distributed Denial-of-Service (DDoS) attacks, steal data, send spam, and allow the attacker to access the device and its conn ...

created by a group of Russian hackers and released in 2010. The FBI included on its list of infected systems "approximately 17 state or local government agencies, including one police department; three airports; two defense contractors; five banks or financial institutions; approximately 30 colleges or universities; approximately 20 hospital or health care companies; and hundreds of businesses." It is present on more than 2.3 million computers worldwide and as of May 2011 remains a threat.

Background

BackdoorCoreflood is a trojan horse that opens a back door on the compromised computer. It acts as a

keylogger Keystroke logging, often referred to as keylogging or keyboard capturing, is the action of recording (logging) the keys struck on a keyboard, typically covertly, so that a person using the keyboard is unaware that their actions are being monitored ...

and gathers user information.

Current status

The FBI has the capability, and recently authorization from the courts, to delete Coreflood from infected computers after receiving written consent. The FBI has reduced the size of the botnet by 90% in the United States and 75% around the world.

References

Botnets Windows trojans {{malware-stub