Browse Definitions :

BACKGROUND IMAGE: iSTOCK/GETTY IMAGES

This content is part of the Essential Guide: How to attack DDoS threats with a solid defense plan
Definition

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

Contributor(s): Matthew Haughn

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

  • compliance audit

    A compliance audit is a comprehensive review of an organization's adherence to regulatory guidelines.

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • Whistleblower Protection Act

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

SearchSecurity

  • Transport Layer Security (TLS)

    Transport Layer Security (TLS) is a protocol that provides authentication, privacy, and data integrity between two communicating ...

  • van Eck phreaking

    Van Eck phreaking is a form of electronic eavesdropping that reverse engineers the electromagnetic fields (EM fields) produced by...

  • zero-trust model (zero trust network)

    The zero trust model is a security model used by IT professionals that requires strict identity and device verification ...

SearchHealthIT

SearchDisasterRecovery

  • cloud insurance

    Cloud insurance is any type of financial or data protection obtained by a cloud service provider. 

  • business continuity software

    Business continuity software is an application or suite designed to make business continuity planning/business continuity ...

  • business continuity policy

    Business continuity policy is the set of standards and guidelines an organization enforces to ensure resilience and proper risk ...

SearchStorage

  • solid-state storage

    Solid-state storage (SSS) is a type of computer storage media made from silicon microchips. SSS stores data electronically ...

  • persistent storage

    Persistent storage is any data storage device that retains data after power to that device is shut off. It is also sometimes ...

  • computational storage

    Computational storage is an information technology (IT) architecture in which data is processed at the storage device level to ...

Close