The US Department of Homeland Security has claimed to have found mobile phone surveillance devices in Washington DC, which could be eavesdropping on phone calls.
They claim to have uncovered the electronic surveillance devices, known as IMSI [International Mobile Subscriber Identity] catchers, which intercept the signals between mobile phones and genuine cell towers.
The IMSI devices are dressed up to appear as if they are legitimate cell towers - effectively being hidden in plain site.
It's already known that the FBI uses similar surveillance tech in its "Stingray" program, which consists suitcase-sized devices that can sweep up data from entire neighbourhoods. But this is the first time the US government has claimed to have found other organisations - presumably foreign agents - using the technique.
The DHS sent a letter on 26 March to Oregon Democrat Senator Ron Wyden, as reported by the Associated Press.
Senior DHS official Christopher Krebs said in the letter that the agency had "observed anomalous activity" that were "consistent" with IMSI catchers in DC but it wasn't sure who was behind the spying. The DHS also noted it needed more funding to better detect these devices.
"NPPD agrees that the use of IMSI catchers by foreign governments may threaten US national and economic security," the letter said, responding to Senator Wyden, who earlier requested answers from the agency in a letter dated November asking about the presence of IMSI catchers in the US capital.
Wyden asked the FCC in the past to investigate Stingray technology, since the agency regulates the airwaves across the US.
"Despite repeated warnings and clear evidence that our phone networks are being exploited by foreign governments and hackers, FCC Chairman Pai has refused to hold the industry accountable and instead is prioritising the interests of his wireless carrier friends over the security of Americans' communications," Wyden said in a statement.
Krebs' letter to Wyden concludes with: "Overall, the NPPD believes the malicious use of IMSI catchers is a real and growing risk".
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