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Eavesdropping Definition

An eavesdropping attack occurs when a hacker intercepts, deletes, or modifies data that is transmitted between two devices. Eavesdropping, also known as sniffing or snooping, relies on unsecured network communications to access data in transit between devices.

To further explain the definition of "attacked with eavesdropping", it typically occurs when a user connects to a network in which traffic is not secured or encrypted and sends sensitive business data to a colleague. The data is transmitted across an open network, which gives an attacker the opportunity to exploit a vulnerability and intercept it via various methods. Eavesdropping attacks can often be difficult to spot. Unlike other forms of cyber attacks, the presence of a bug or listening device may not adversely affect the performance of devices and networks.

Eavesdropping Methods

With eavesdropping, attackers can use various methods to launch attacks that typically involve the use of various eavesdropping devices to listen in on conversations and review network activity.

A typical example of an electronic listening device is a concealed bug physically placed in a home or office. This could occur by leaving a bug under a chair or on a table, or by concealing a microphone within an inconspicuous object like a pen or a bag. This is a simple approach but could lead to more sophisticated, difficult-to-detect devices being installed, such as microphones within lamps or ceiling lights, books on a bookshelf, or in picture frames on the wall.

Despite all the number of technological advances making digital eavesdropping increasingly easy in this day and age, many attacks still rely on intercepting telephones. That is because telephones have electric power, built-in microphones, speakers, space for hiding bugs, and are easy to quickly install a bug on. Eavesdropping attackers can monitor conversations in the room the telephone is in and calls to telephones anywhere else in the world.

Modern-day computerized phone system make it possible to intercept phones electronically without direct access to the device. Attackers can send signals down the telephone line and transmit any conversations that take place in the same room, even if the handset is not active. Similarly, computers have sophisticated communication tools that enable eavesdropping attackers to intercept communication activity, from voice conversations, online chats, and even bugs in keyboards to log what text users are typing.

Computers also emit electromagnetic radiation that sophisticated eavesdroppers can use to reconstruct a computer screen’s contents. These signals can be carried up to a few hundred feet and extended further through cables and telephone lines, which can be used as antennas.

Pickup Device

Attackers can use devices that pick up sound or images, such as microphones and video cameras, and convert them into an electrical format to eavesdrop on targets. Ideally, it will be an electrical device that uses power sources in the target room, which eliminates the need for the attacker to access the room to recharge the device or replace its batteries. 

Some listening devices are capable of storing digital information and transmitting it to a listening post. Attackers may also use mini amplifiers that enable them to remove background noise.

Transmission Link

A transmission link between a pickup device and the attacker’s receiver can be tapped for eavesdropping purposes. This can be done in the form of a radiofrequency transmission or a wire, which includes active or unused telephone lines, electrical wires, or ungrounded electrical conduits. Some transmitters can operate continuously, but a more sophisticated approach involves remote activation.

Listening Post

A listening post is used to transmit conversations intercepted by bugs on telephones. When a telephone is picked up to make or take a call, it triggers a recorder that is automatically turned off when the call is ended. 

Listening posts are secure areas in which signals can be monitored, recorded, or retransmitted by the attacker for processing purposes. It can be located anywhere from the next room to the telephone up to a few blocks away. The listening post will have voice-activated equipment available to eavesdrop on and record any activity.

Weak Passwords

Weak passwords make it easier for attackers to gain unauthorized access to user accounts, which gives them a route into corporate systems and networks. This includes hackers being able to compromise confidential communication channels, intercept activity and conversations between colleagues, and steal sensitive or valuable business data.

Open Networks

Users who connect to open networks that do not require passwords and do not use encryption to transmit data provide an ideal situation for attackers to eavesdrop. Hackers can monitor user activity and snoop on communications that take place on the network.

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What Does Eavesdropping Mean For Your Business?

Eavesdropping attacks can result in the loss of critical business information, users’ privacy being intercepted, and lead to wider attacks and identity theft. 

A good example of the impact eavesdropping attacks can have is the increasing use of digital assistants like Amazon Alexa and Google Home. These assistants make users’ lives easier but are also easy for attackers to eavesdrop on and gain private information. 

The impact of eavesdropping can include:

  1. Financial loss: Cyberattackers can use their access to sensitive information, such as corporate data, business secrets, or user passwords, for financial gain. This includes selling the data to third parties or competitors or holding organizations or individuals to ransom by blocking access to data as part of a Ransomware attack. Furthermore, any incident of data loss runs the risk of the organization suffering reputation damage, which could lead to losing customers, and as a result, financial loss.
  2. Identity theft: Eavesdropping attackers can listen in on conversations that occur within applications that users presume are secure. This can lead to them unwittingly revealing sensitive information that attackers can use to steal their credentials and carry out wider identity theft attacks. 

Privacy loss: The theft of confidential information could lead to businesses and users suffering privacy loss. Attackers that carry out eavesdropping attacks can intercept vital business details, conversations, and exchanges that affect users’ privacy.

How To Prevent Eavesdropping Attacks

The increasingly digital world makes it easier for hackers to intercept corporate information and user conversations. However, it also presents opportunities for organizations to prevent attackers’ malicious intent. Common methods that help prevent eavesdropping attacks include: 

  1. Military-grade encryption: One of the best ways to prevent eavesdropping attacks is to encrypt data in transmission and private conversations. Encryption blocks attackers' ability to read data exchanged between two parties. For example, military-grade encryption provides 256-bit encryption, which is near impossible for an attacker to decode.
  2. Spread awareness: Ensuring that employees are aware of the risks and dangers of cybersecurity is a crucial first line in protecting organizations from any cyberattack. This is very much the case with eavesdropping attacks, so organizations must provide training that advises users about how attackers go about launching the attacks. Employees need to understand the methods attackers use to listen in to conversations, follow best practices to limit the risk, and be constantly aware of the signs of an attack. They should also avoid downloading insecure applications or software and never connect to weak or open networks.
  3. Network segmentation: Organizations can limit the possibilities of attackers eavesdropping on networks by restricting their availability. Network segmentation enables organizations to limit resources to only the people that require access to them. For example, people on a marketing team do not require access to HR systems and people on the IT team do not need view to financial information. Network segmentation divides the network up, which decongests traffic, prevents unwanted activity, and improves security by preventing unauthorized access.
  4. Avoid shady links: Related to spreading awareness is the need to avoid shady or untrusted links. Eavesdropping attackers can spread malicious software that includes eavesdropping malware through shady links. Users should only download official software from trusted resources and providers, and only download applications from official app stores.
  5. Update and patch software: Attackers can also exploit vulnerabilities in software to target organizations and users. This makes it crucial to turn on automatic updates and ensure all software is patched immediately as a new release or update is available.
  6. Physical security: Organizations can also protect their data and users through physical security measures in their office spaces. This is crucial to protecting the office from unauthorized people who may drop physical bugs on desks, phones, and more.
  7. Shielding: The risk of eavesdropping through computer radiation can be prevented by installing security measures and shielding. For example, TEMPEST-protected computers enable organizations to block unintended radiation and keep their data and users secure.

How Fortinet Can Help

Fortinet provides a range of solutions that enable organizations to keep their networks safe from intruders and prevent unauthorized access to their systems.

Fortinet next-generation firewalls (NGFWs) filter network traffic to protect organizations from internal and external security threats. The firewalls also possess advanced features that enable deeper content inspection, the inspection and blocking of attacks, and intrusion prevention. Organizations gain advanced visibility across their attack surface, which is crucial to preventing eavesdropping. Fortinet web application firewalls (WAFs) also defend organizations’ web applications from known and evolving cyber threats, identify anomalous behavior, and block malicious activity. 

Further, Fortinet enables organizations to establish a zero-trust approach to network access. This ensures they have full visibility of who and what is accessing their networks and guarantees only the right people have the right level of access to the right resources at the right time.


What is the purpose of eavesdropping?

Eavesdropping is used by cyberattackers to intercept communication and steal sensitive data in transit. Hackers use pickup devices that pick up sound and images, such as microphones and cameras, and convert them into an electrical format to eavesdrop on victims. They may also use transmission links and listening posts to intercept and record conversations and data.

How do hackers eavesdrop?

Eavesdropping attacks occur when hackers intercept, delete, or modify data that is transmitted between devices. Also known as sniffing or snooping, this process typically sees attackers exploit unsecured or open network communications and unencrypted data, which enables them to access data in transit between devices. Hackers can also eavesdrop by placing bugs on telephones, which allow them to intercept and record communication. They can also take advantage of poor security practices, such as the use of weak passwords and unpatched software, to gain a route into corporate networks and steal sensitive data.

What are the types of eavesdropping attacks?

Eavesdropping attacks target telephones, smartphones, and computers. This can be used to steal data for financial gain, either by selling data to third parties and competitors or by causing financial damage to an organization. Attackers can also use eavesdropping to commit identity theft by stealing sensitive information and using it to carry out wider attacks through stolen login credentials. Eavesdropping attacks also result in privacy loss, as confidential information can be intercepted, stolen, and sold.