Telstar Satellite: the Launch of the Modern World

by Marius Marinescu / 18 July

Trans-Atlantic television and other communications became a reality as the Telstar communications satellite was launched. A product of AT&T Bell Laboratories, the satellite was the first orbiting international communications satellite that sent information to tracking stations on both sides of the Atlantic Ocean. Initial enthusiasm for making phone calls via the satellite waned after users realized there was a half-second delay as a result of the 25,000-mile transmission path.

Even if nowadays it seems like a phone call is a regular thing, IT professionals have dealt with many difficulties in the past to make fixed phone calls a reality. Nowadays we are concerned with making our conversations safer by solving the different security breaches we are confronted with, but back then people had other issues.

Quick recap for the millennials: long before everyone had a smartphone or two, the implementation of a telephone was quite different than today. Most telephones had real, physical buttons. Even more bizarrely, these phones were connected to other phones through physical wires. Weird, right? These were called “landlines”, a technology that is still employed in many households around the world.

It gets even more bizarre. Some phones were wireless (quite just like your smartphone) but they couldn’t get a signal more than a few hundred feet away from your house for some reason. These were “cordless telephones”. Many hackers are working on deconstructing the security behind these cordless phones for a few years now and found these cordless phones aren’t secure at all.

While nothing is 100% secure, many people thought that DECT and 5.8GHz phones were safe, at least more so than the cordless phones from the 80s and 90s. While DECT has been broken for a long time, 5.8GHz phones were considered to be safer than 900mhz phones, as scanners are harder to come by in the microwave bands, because very few people have a duplex microwave transceiver sitting around. But everything is bound to happen eventually.

With the advent of cheap SDR, hackers demonstrated that listening to and intercepting any phone call they want is actually possible. Using a duplex microwave transceiver (very cheap at ~$300 for the intended purpose) they freely explored the radio system inside these cordless phones. After taking a duplex microwave transceiver to a cordless phone, hackers found the phone technically didn’t operate in the 5.8 GHz band. Control signals, such as pairing a handset to a base station, happened at 900 MHz. Here, a simple replay attack was enough to get the handset to ring. It gets worse: simply by looking at the 5.8 GHz band with a transceiver, they found an FM-modulated voice channel when the handset was on. That’s right: the phone transmits the voice signal without any encryption whatsoever.

This isn’t the first time hackers found a complete lack of security in cordless phones. A while ago, they explored the DECT 6.0 standard, a European cordless phone standard for PBX and VOIP. There was no security there, either.

It would be chilling if landlines were as spread today as they were 20 some years ago, because the tools to perform a landline hack are freely available and thoroughly documented.