S 4.254 Secure usage of wireless keyboards and mice

Initiation responsibility: IT Security Officer, Head of IT

Implementation responsibility: User, Administrator

Wireless keyboards and mice are peripheral devices that communicate wirelessly with a computer using radio or infrared interfaces with a receiver module which is connected to a COM port, PS2 interface or USB connection of the computer.

Since there is no electrical connection between such devices and the computer, wireless input devices need their own power supply in the form of normal or rechargeable batteries. To enable a long service life, it is essential for such devices to consume as little power as possible. With the technology used today, devices with infrared technology consume more power than those with a radio interface.

The operating frequencies of the systems are all in license-free frequency ranges. The majority of wireless mice and wireless keyboards transmit in the 27 MHz band and have two radio channels. Some wireless devices operate in the 2.4 GHz band.

The range of radio systems is usually 2 to 5 meters. In contrast to systems based on infrared technology, radio systems do not need a direct line of sight between the sender and receiver. The range is highly dependent on the environmental conditions. Other devices transmitting in the same frequency range such as mobile radio telephones, radio-controlled toys, radio-controlled garage door openers, or WLAN connections in the 2.4 GHz band can significantly interfere with the operation of the systems and reduce their range. Metal obstructions (steel reinforcements, steel cabinets and other such items) can cause the technology to fail.

The range stated by a manufacturer for a radio application specifies the distance at which their devices are able to reliably transmit data. In the case of devices equipped with cheap receiver technology, this functional range is generally smaller than the distance at which it is still possible to receive, record and process the signals transmitted using directional antennas and high-quality receiver electronics. There is therefore still a risk of someone who is located at a distance greater than the functional range being able to listen in on a transmission.

One problem with radio-based input devices is their lack of protection against eavesdropping. The radio signal transmitted can be received and recorded by third parties. If these radio signals are not securely encrypted, then it is easy to read this data. There are numerous wireless keyboard systems on the market that transmit the signals resulting from the keystrokes without any encryption, which means third parties can eavesdrop on the data transmitted. In many cases, a third party only needs a second receiver from the same manufacturer to view the signals received on another computer.

Systems communicating on the basis of an infrared technology usually use the IrDA standard specified by the Infrared Data Association. The IrDA standard does not specify any security mechanisms against eavesdropping on the data traffic. The data is protected against transmission errors at the protocol level using checksum methods. Security mechanisms such as authentication, cryptographic integrity protection, and encryption are not available. To a certain extent, transmissions are protected due to the very limited range of the infrared beams and the need for a direct line of sight. The security afforded by these systems, though, is less than that afforded by cabled input devices due to the potential for scattering.

Some manufacturers offer products with proprietary security solutions. However, it is impossible to ascertain the security of such solutions since the algorithms used are generally kept secret by the manufacturers.

To enable devices constructed identically to be operated at the same time, most manufacturers have equipped their devices with unique identification numbers. Different principles are applied in this case. For example, a certain value obtained from a pool of IDs can be permanently assigned to a device or a new ID may be generated at random by the software after changing the battery.

There are also products available on the market that communicate via Bluetooth. When the Bluetooth security features are implemented and configured correctly, Bluetooth generally offers a higher level of protection than radio systems using a proprietary technology.

Finally, it must be mentioned that keyboards are subject to the threats posed by eavesdropping due to the electromagnetic emissions from the keyboard matrix and the connection cable (see also S 4.89 Emission security). This also applies to wireless keyboards. However, the risk of eavesdropping is generally much lower when using keyboards with cables than when using radio communication routes as in the case of wireless input devices.

A large number of wireless keyboards and wireless mice send their information to the computers using radio waves or infrared light but without taking any security precautions. It is not difficult for third parties to intercept this information or even manipulate it. For this reason, it is generally not advised to use such systems from an IT security perspective.

It is impossible to assess the quality of the security offered by systems with proprietary security safeguards whose security has not been certified. The users in this case run the risk that the unevaluated solution of the manufacturer only offers a minimum level security that is not nearly high enough to protect their data effectively.

Wireless systems based on standards like Bluetooth and in which the security mechanisms have been implemented and enabled correctly offer greater protection. In sensitive areas, though, it is better to avoid using wireless keyboards, wireless mice, and infrared products entirely.

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