What is Eavesdropping?


Merriam-Webster dictionary defines eavesdropping as the act of secretly listening to something private.

In computer security, eavesdropping refers to the interception of communication between two parties by a malicious third party.

An eavesdropping attack, also known as snooping or sniffing attack, is the theft of information transmitted over a network by a digital device such as a computer, smartphone, or IoT device. The attack exploits vulnerabilities in unsecured network communications to access data illegally.

Key Takeaways

  • Eavesdropping is secretly or stealthily listening to others’ private communications without their consent to gather information.
  • Eavesdropping is regarded as unethical and illegal in many jurisdictions
  • Eavesdropping attack, also known as sniffing or snooping attack, exploits vulnerabilities in unsecured network communications to access data illegally.

Eavesdropping Attack Motivations and Impacts

Attackers perform eavesdropping activities to steal and sell sensitive financial, business, and personal information for monetary gains and other criminal purposes.

A hacker can steal bank account information to make unauthorized purchases and transfer money. Eavesdropping attack leads to the theft of personal data that criminals use to steal identities.

Sometimes, attackers deploy eavesdropping technique to uncover incriminating evidence against someone. They use such information to blackmail victims for emotional leverage and financial gains.  

Cybercriminals can steal passwords through eavesdropping attacks. They utilize stolen credentials to access private assets in a digital network.

Eavesdropping attacks result in loss of privacy. Attackers deploy techniques to absorb important business and personal information, ideas, and conversations between two parties, thereby affecting their privacy.

How Eavesdropping Attack Occurs

An eavesdropping incident is difficult to detect since the network activities appear to be operating normally.

In eavesdropping attacks, hackers look for a weakened connection between a client and a server. They deploy various tactics to reroute network traffic. In some cases, an attacker can install a network monitoring software or a sniffer to intercept data between sender and receiver.

Hackers also use legitimate applications that security teams use to monitor and analyze network traffic, such as Wireshark, tcpdump, and Snort, to spot and exploit vulnerabilities in a network.

Eavesdropping Techniques  

Hackers devise new ways to eavesdrop digital communications. Examples of attack techniques include:

  • Voice-Over-IP (VoIP): attackers record IP-based calls using protocol analyzers. They convert the data into audio files for further analysis. During VoIP eavesdropping, a hacker infiltrates the network through a compromised VoIP device, such as a switch, cable, or internet. VoIP eavesdropping is an example of a passive attack.
  • Data Sniffing: in this attack, cybercriminals target local networks with HUB. The attacker users a sniffer that accepts incoming data for analysis. Sniffers also collect unencrypted information broadcasted on open ports. Data sniffing is an active eavesdropping attack where an attacker injects, modifies, or block data packets. Man-in-the-middle (MitM) attack is a common data sniffing technique.
  • Microphone Recording: a different eavesdropping scenario involves using microphones and recorders to listen to people’s conversations in the real world. In other cases, cybercriminals hack phones by remotely activating the device’s speaker function. Remote microphone hacking also affects laptops and IoT smart home devices.

Preventing Eavesdropping Attacks

Follow these tips to prevent eavesdropping attacks:

  • Use a firewall to monitor and block malicious network traffic
  • Keep the antivirus software updated to detect and deter malicious programs
  • Use a virtual private network (VPN) to encrypt confidential information on public networks
  • Implement a robust access control mechanism with a strong and unique password for every site
  • Update your device’s operating systems to patch detected vulnerabilities
  • Encrypt information before transferring it using digital networks
  • Authenticate incoming data packets to prevent spoofed packets that hackers use to perpetrate IP and MAC address spoofing
  • Educate employees about eavesdropping attack risks and the best practices to deter them
  • Businesses can segment their networks and put confidential data in highly secured segments