CISA defines a virus as a malicious program that spreads by first infecting files or the system areas of a computer or network router’s hard drive and then making copies of itself.

A virus infecting devices or networks can often lead to detrimental effects, including data corruption, unauthorized access, and system instability.

Unlike other forms of malware, a virus requires user engagements and actions to spread, which typically occurs through the opening of infected files or applications.

Characteristics of a Virus

Viruses are usually characterized by their ability to self-replicate and spread. They attach themselves to legitimate programs or files, including documents, spreadsheets and applications.

When a user unknowingly opens an infected file, the virus is then activated, allowing it to launch its “payload.” The “payload” is then responsible for executing a number of activities such as displaying a message, deleting files, stealing sensitive information or encrypting data.

Types of Virus

There are several types of known virus which can be catergorized based on their behaviors and methods of distribution:

  1. File Infector Viruses: These viruses attach themselves to executable files and are activated when the infected file is run on a device.
  2. Macro Viruses: These target applications, such as Microsoft Excel, using macro programming features to execute malicious code whenever a document is opened.
  3. Boot Sector Viruses: These will infect the master boot record of a hard drive, allowing the virus to execute when the computer starts up.
  4. Polymorphic Viruses: Each time it infects a new file, a polymorphic virus will change its code and signature, making it harder for antivirus and other cybersecurity software to detect.
  5. Multipartie Viruses: These viruses will use multiple methods to infect a system, including targeting both files and boot sectors simultaneously.

Virus – Infection and Spread

Viruses can typically spread through various means, including:

  • Removeable Media: USB drives or external hard drives that become infected can transmit the virus from one system to another.
  • File Sharing: Downloading software or other files from unreliable sources increases the risk of infection.
  • Email Attachments: Attachments infected with a malicious virus can be sent in emails, appearing to come from a legitimate source, causing unsuspecting users to download and open them.
  • Network Connections: Viruses can spread across networks, infecting multiple devices connected to the same system.

The Impact of Viruses on Systems

When viruses infect systems, there can be significant impacts which can result in:

  • Unauthorized Access: Certain viruses are designed to create backdoors, allowing attackers to gain unauthorized access to systems and data on the infected device or network.
  • Data Loss: Corruption, encryption or deletion of files caused by viruses can result in significant data loss.
  • Disruption: Systems infected with viruses will often experience slow performance, frequent crashes, and instability, causing disruption to an organization’s daily operations.
  • Financial Implications: Substantial costs related to data recovery, system repair, reputation damage and compliance issues can be a consequence of a virus infection.

Prevention and Mitigation

A layered, multi-faceted approach is required to prevent virus infections and mitigate the impact on an organization:

  • Antivirus Software: As the name suggests, installing and regularly updating antivirus software will help to detect and eliminate viruses.
  • Layered Cybersecurity Stack: Using a layered approach to cybersecurity is key to mitigating the risk of virus infections and other cyberthreats. Using a number of effective, efficient tools, paired with innovative technologies such as ADX, will decrease the risk of falling victim to a cyberthreat.
  • User Education: Training employees to be wary of suspicious emails and files, along with recognizing characteristics of other cyberthreats, can reduce the likelihood of infections.
  • Regular Backups: Ensuring regular backups of important data are done, either manually or automatically, helps with the restoration of information in the event of data loss, encryption or deletion as a result of a virus attack.
  • Software Updates: Updating operating systems and applications regularly, or as soon as a new update is available, helps limit the chance of a virus attack through vulnerabilities.