Browse Definitions :
Definition

command-and-control server (C&C server)

Contributor(s): Matthew Haughn
This definition is part of our Essential Guide: How to attack DDoS threats with a solid defense plan

A command and control server (C&C server) is a computer that issues directives to digital devices that have been infected with rootkits or other types of malware, such as ransomware. C&C servers can be used to create powerful networks of infected devices capable of carrying out distributed denial-of-service (DDoS) attacks, stealing data, deleting data or encrypting data in order to carry out an extortion scheme. In the past, a C&C server was often under an attacker's physical control and could remain active for several years. Today, C&C servers generally have a short shelf life; they often reside in legitimate cloud services and use automated domain generation algorithms (DGAs) to make it more difficult for law enforcement and white hat malware hunters to locate them. 

A malicious network under a C&C server's control is called a botnet and the network nodes that belong to the botnet are sometimes referred to as zombies. In a traditional botnet, the bots are infected with a Trojan horse and use Internet Relay Chat (IRC) to communicate with a central C&C server. These botnets were often used to distribute spam or malware and gather misappropriated information, such as credit card numbers. 

Popular botnet topologies include:

  • Star topology - the bots are organized around a central server.
  • Multi-server topology - there are multiple C&C servers for redundancy.
  • Hierarchical topology - multiple C&C servers are organized into tiered groups.
  • Random topology - coopted computers communicate as a peer-to-peer botnet (P2P botnet).

Since IRC communication was typically used to command botnets, it is often guarded against. This has motivated the drive for more covert ways for C&C servers to issue commands. Alternative channels used for botnet command include JPG images, Microsoft Word files and posts from LinkedIn or Twitter dummy accounts.

Learn more about botnet command and control in this video:

This was last updated in January 2017

Continue Reading About command-and-control server (C&C server)

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • Whistleblower Protection Act

    The Whistleblower Protection Act of 1989 is a law that protects federal government employees in the United States from ...

  • smart contract

    A smart contract, also known as a cryptocontract, is a computer program that directly controls the transfer of digital currencies...

  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

SearchSecurity

  • certificate authority (CA)

    A certificate authority (CA) is a trusted entity that issues digital certificates, which are data files used to cryptographically...

  • hacktivism

    Hacktivism is the act of hacking, or breaking into a computer system, for a politically or socially motivated purpose.

  • advanced persistent threat (APT)

    An advanced persistent threat (APT) is a prolonged and targeted cyberattack in which an intruder gains access to a network and ...

SearchHealthIT

  • Cerner Corp.

    Cerner Corp. is a public company in North Kansas City, Mo., that provides various health information technologies, ranging from ...

  • clinical decision support system (CDSS)

    A clinical decision support system (CDSS) is an application that analyzes data to help healthcare providers make decisions and ...

  • Health IT (health information technology)

    Health IT (health information technology) is the area of IT involving the design, development, creation, use and maintenance of ...

SearchDisasterRecovery

  • tabletop exercise (TTX)

    A tabletop exercise (TTX) is a disaster preparedness activity that takes participants through the process of dealing with a ...

  • risk mitigation

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a data center.

  • ransomware recovery

    Ransomware recovery is the process of resuming options following a cyberattack that demands payment in exchange for unlocking ...

SearchStorage

  • SSD (solid-state drive)

    An SSD (solid-state drive) is a type of nonvolatile storage media that stores persistent data on solid-state flash memory.

  • file system

    In a computer, a file system -- sometimes written filesystem -- is the way in which files are named and where they are placed ...

  • storage virtualization

    Storage virtualization is the pooling of physical storage from multiple storage devices into what appears to be a single storage ...

Close