What Are Eavesdropping Attacks? | Fortinet (2024)

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.

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.

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.