Dialers, also called analog dial-up hackers and Demon-Dialers, can attack individuals and enterprises that have dial-up connections into their homes or private networks. The ubiquity of cable and DSL will someday render this technique obsolete, but it is still a threat. Dialers identify the phone numbers able to connect with a computer modem and automatically dial a range of phone numbers, predefined numerically. They capture and record all those numbers that successfully connect to the modem. Some Dialers can also identify the operating system running in the computer and may also conduct automated penetration testing. To do this, the Dialer cycles through a preconfigured list of common user names and passwords in an attempt to gain access to the system. Electronic versions of local phone books are easily available. Hackers can include phone book data in their Dialers scripts. Another Dialer technique is identification of the exchange. For example, hackers learn that the main phone number of a large company, "The ABC Corporation" is 111-111-1010. They set up War-Dialing sessions to call the 10,000 numbers that could possibly be derived from the last four numbers of this main number (111-111-XXXX). This is known as "phone footprinting." Dialer hardware and software requirements are fairly basic. For hardware, hackers only need a basic PC with two standard COM ports and a serial card with which to add additional ports. Common commercial software programs are ToneLoc, THC-Scan and PhoneSweep. Dialers can also have a legitimate purpose. Commercial Dialers are used by network administrators to identify unauthorized modems on an enterprise network. |