Linked List: November 21, 2023

Tuesday, 21 November 2023

Background Information on Hemisphere/DAS 

More information on the aforelinked secret program that provides U.S. law enforcement with trillions of phone call records, including location data, from the EFF:

“Hemisphere” came to light amidst the public uproar over revelations that the NSA had been collecting phone records on millions of innocent people. However, Hemisphere wasn’t a program revealed by Edward Snowden’s leaks, but rather its exposure was pure serendipity: a citizen activist in Seattle discovered the program when shocking presentations outlining the program were provided to him in response to regular old public records requests.

This slide deck hosted by the EFF is one of those presentations, and worth your attention. The system’s capabilities are terrifying. From page 9 of that deck, highlighting Hemisphere’s “Special Features”:

  • Dropped Phones — Hemisphere uses special software that analyzes the calling pattern of a previous target phone to find the new number. Hemisphere has been averaging above a 90% success rate when searching for dropped phones.

  • Additional Phones — Hemisphere utilizes a similar process to determine additional cell phones the target is using that are unknown to law enforcement.

So if a target throws away their phone, switches to a new burner phone, but continues calling the same people, Hemisphere claims a 90 percent success rate identifying that new phone.

  • Advanced Results — Hemisphere is able to provide two levels of call detail records for one target number by examining the direct contacts for the original target, and identifying possibly significant numbers that might return useful CDRs.

So the system analyzes not just the phone records of the target, but the records of every single number the target calls.

Page 20 of the deck is highly redacted:

  • Hemisphere can capture data regarding local calls, long distance calls, international calls, cellular calls [???]

  • Hemisphere does NOT capture █████████████████████████ subscriber information [???]

  • Highlights of any basic request include: █████████████████████████ █████████████████████████████████ temporary roaming and location data, and traffic associated with international numbers

I’m using “[???]” to denote spots where I suspect information has been redacted, and “█” to indicate obvious redactions. I sure would love to know what’s redacted there. Again, my mind runs to text messages.

Secretive U.S. Surveillance Program Gives Cops Access to Trillions of U.S. Phone Records 

Dell Cameron and Dhruv Mehrotra, reporting for Wired:

A little-known surveillance program tracks more than a trillion domestic phone records within the United States each year, according to a letter Wired obtained that was sent by US senator Ron Wyden to the Department of Justice (DOJ) on Sunday, challenging the program’s legality.

According to the letter, a surveillance program now known as Data Analytical Services (DAS) has for more than a decade allowed federal, state, and local law enforcement agencies to mine the details of Americans’ calls, analyzing the phone records of countless people who are not suspected of any crime, including victims. Using a technique known as chain analysis, the program targets not only those in direct phone contact with a criminal suspect but anyone with whom those individuals have been in contact as well.

The DAS program, formerly known as Hemisphere, is run in coordination with the telecom giant AT&T, which captures and conducts analysis of US call records for law enforcement agencies, from local police and sheriffs’ departments to US customs offices and postal inspectors across the country, according to a White House memo reviewed by Wired. Records show that the White House has, for the past decade, provided more than $6 million to the program, which allows the targeting of the records of any calls that use AT&T’s infrastructure — a maze of routers and switches that crisscross the United States.

In a letter to US attorney general Merrick Garland on Sunday, Wyden wrote that he had “serious concerns about the legality” of the DAS program, adding that “troubling information” he’d received “would justifiably outrage many Americans and other members of Congress.” That information, which Wyden says the DOJ confidentially provided to him, is considered “sensitive but unclassified” by the US government, meaning that while it poses no risk to national security, federal officials, like Wyden, are forbidden from disclosing it to the public, according to the senator’s letter.

Ron Wyden and his office are indispensable on matters related to government surveillance. A few non-obvious aspects worth considering regarding the DAS/Hemisphere program:

  • The information collected by DAS includes location data.

  • This is not just about AT&T wireless customers and their phone calls. This is related to the entire U.S. phone system infrastructure — the old Ma Bell. Landline calls and calls from Verizon and T-Mobile cellular customers get routed through this AT&T system, and are thus surveilled by this same system. You can use over-the-top services like iMessage, FaceTime, WhatsApp, or Signal to avoid DAS, but if you place calls using the traditional phone system, you could be impacted even if you’re not an AT&T customer — and you won’t ever know, because you have no idea how your phone calls are routed.

  • It is completely unclear to me whether DAS/Hemisphere collects text messages — SMS, MMS, RCS — in addition to voice calls. I’ve spent my afternoon trying to find out, and the only answer I’ve gotten is it’s unclear. I hope text messages are not included, but until we get a definitive answer, it’s only safe to assume that text messages are included. (If anyone reading this knows whether DAS includes text message records, please let me know.)