T 5.44 Abuse of remote access ports for management functions of private branch exchanges

Private branch exchanges (PBX systems) provide remote access ports for management functions. These access ports can be used for performing all administration and maintenance work as well as other management functions such as alarm signalling and processing.

Such remote access ports are particularly useful in PBX system clusters (Corporate Networks), and are sometimes indispensable. The type of remote access can be differentiated as follows:

• IP-based access via data networks,
• "modem" access via dedicated management ports, and
• direct dialling via DISA (Direct Inward System Access).

Furthermore, newer protocols such as QSig and some other proprietary protocols already include management functions in the signalling spectrum. This results in a certain potential for misuse.

When a system has inadequately secured remote maintenance ports, it is possible for hackers to obtain access to the management programmes of the PBX system. After cracking the system password, it may eventually be possible for them to execute any administration task. The resulting damage may include complete failure of the system, serious operational disruptions, loss of confidentiality of all data stored on the affected system, or significant financial losses e.g. due to call charges fraud.