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Passive attack

(also eavesdropping, sniffing, or traffic monitoring)

Passive attack definition

A passive attack refers to an unauthorized attempt to covertly access and monitor network traffic without actually altering or tampering with the data. The main goal of this type of cyberattack is to quietly gather sensitive information, such as private login details, personal data, or valuable intellectual property, without raising any red flags. Passive attacks can be particularly tricky to detect compared to active attacks since they don't directly interfere with the normal functioning of the system or network.

See also: packet sniffing, active attack, network security protocols

Passive attack examples

  • Packet sniffing: An attacker monitors unencrypted network packets to gather information, such as usernames, passwords, or email content.
  • Wiretapping: Unauthorized interception of phone calls or other communication signals to gain access to sensitive information.

Comparing passive and active attacks

Passive attacks focus on gathering information discreetly without alerting the victim. In contrast, active attacks involve manipulating or altering data, directly attacking the system, or disrupting network services.

Pros and cons of passive attacks


  • Passive attacks are stealthier and more difficult to detect, allowing attackers to collect information for an extended period.


  • Passive attacks provide limited access to information because they rely on intercepted data rather than system manipulation.

Tips to prevent passive attacks

  • Use encryption for sensitive data and communications.
  • Employ secure protocols like HTTPS and secure Wi-Fi connections.
  • Implement network monitoring tools to detect unusual traffic patterns.
  • Use NordVPN to encrypt your internet connection and protect against eavesdropping.