What is GPS?
GPS is a United States government-owned satellite navigation system, known as the Global Positioning System, that operates in medium Earth orbit and provides positioning, navigation, and timing services. Discussion around it has centered on how easily its timing signals can be disrupted, and on how its long-established orbital assets differ from newer alternatives.
Release history
- Sep 2026 - Sean MacKirdy said the GPS constellation’s assets have a different threat profile and cyber landscape than newer systems, having been on orbit since the 1970s and 1980s.
- Sep 2026 - Sean MacKirdy said those older assets are not reprogrammable in the sense that only minor software upgrades can be made along the way.
- Sep 2026 - An unnamed speaker said that with a software-defined radio costing less than $1,000, an antenna pointed at a data center’s roof antenna could impersonate the GPS network and inject its own time.
In the discourse
Attributed discussion of GPS.
A software-defined radio capable of spoofing GPS time signals to a data center rooftop antenna can be purchased for less than $1,000, enabling arbitrary time injection into a network.
“If I had a software defined radio, which is a piece of kit that you can buy for less than $1,000, probably significantly less than $1,000, and pointed my antenna at the receiving antenna on the roof of a data center, I could pretend to be the GPS network, and I could inject my own time.”<UNKNOWN> · 6 Sep 2026
The GPS constellation dates to the 1970s and 1980s, making it a decades-old legacy system with a fundamentally different and more constrained cyber defense posture than modern LEO constellations.
“Those assets have a different threat profile or different cyber landscape than something that's been on orbit like the GPS constellation since the 1970s 1980s right.”Sean MacKirdy · 20 Sep 2026
GPS constellation satellites support only minor software upgrades and are not truly reprogrammable, putting them closer to legacy hardware than to modern software-defined LEO satellites.
“Those aren't reprogrammable in the sense that you can do some minor software upgrades along the way.”Sean MacKirdy · 20 Sep 2026
Phrack, not the security industry, was the first to surface that GPS signals are trivially easy to jam, predating wide public awareness by roughly two years before cheap jammers became commercially available from China.
“It was Frank first who released that article and got this idea out there that hey GPS is actually very easy to jam. No one ever thought about that.”Jack Rhysider · 3 Feb 2026