S 5.51 Security-related requirements for communications links between telecommuting workstations and the institution

Initiation responsibility: Head of IT, IT Security Officer

Implementation responsibility: Telecommuter, Administrator

When data is transmitted in the context of telecommuting between a telecommuting computer and the communications computer of the organisation, business information will usually be transmitted over public communication networks. Since neither the organisation nor the telecommuter has an influence on whether or not the confidentiality, integrity, and availability are protected in a public communication network, additional safeguards must be implemented.

In general, data transmissions between the telecommuting computer and the organisation should meet the following security requirements:

• Ensuring the confidentiality of the transmitted data: It must be ensured through the use of an adequately secure encryption mechanism that it is impossible to deduce any information on the contents of the data by listening in on the communication between the telecommuting computer and the organisation's communications computer. In addition to using a suitable encryption procedure, it is also necessary to use appropriate key management and to periodically replace the keys.
• Ensuring the integrity of the transmitted data: The transmission protocols used must be able to detect any data changed randomly during transmission and correct these changes. To enable detection of manipulations during transmission of the data, the data should be signed and/or encrypted.
• Ensuring the availability of the data transmission: If time delays while telecommuting are very difficult to tolerate, then a redundantly designed public communication network should be selected as the transmission route so that the failure of one transmission route will not result in a total breakdown of communications. A redundant network connection between the telecommuting computer and the interface at the organisation does not necessarily have to be used.
• Ensuring the authenticity of the data: When transmitting data between the telecommuting computer and the organisation, it must be possible to reliably determine if the right parties are communicating so that masquerades can be ruled out. This means that data marked as being sent by the telecommuting computer actually originated from this computer. Similarly, it must also be possible without any doubt to trace the origin of the data coming from the organisation back to the organisation itself.
• Ensuring the reproducibility of the data transmission: Logging functions that enable you to determine after transmission which data were transmitted at what time and to whom can be used to ensure a transmission can be reproduced.
• Ensuring the data have been received: If it is important to be able to determine if the data have been received correctly while telecommuting, then acknowledgement mechanisms enabling you to determine if the recipient received the data correctly can be used.

The strength of the mechanisms required for this purpose depend on the protection requirements of the data transmitted.

Review questions:

• Do the communication protocols and security mechanisms used meet the requirements for the communication connection between the telecommuting computer and the organisation?
• Are the confidentiality, integrity, and authenticity of the data transmitted between the telecommuting computer and the organisation as well as the authenticity of the communication partners guaranteed?