You Break It, We Fix It

February 26, 2022 by Elliot Williams 44 Comments

Apple’s AirTags have caused a stir, but for all the wrong reasons. First, they turn all iPhones into Bluetooth LE beacon repeaters, without the owner’s permission. The phones listen for the AirTags, encrypt their location, and send the data on to the iCloud, where the tag’s owner can decrypt the location and track it down. Bad people have figured out that this lets them track their targets without their knowledge, turning all iPhone users into potential accomplices to stalkings, or worse.

Naturally, Apple has tried to respond by implementing some privacy-protecting features. But they’re imperfect to the point of being almost useless. For instance, AirTags now beep once they’ve been out of range of their owner’s phone for a while, which would surely alert the target that they’re being tracked, right? Well, unless the evil-doer took the speaker out, or bought one with the speaker already removed — and there’s a surprising market for these online.

If you want to know that you’re being traced, Apple “innovated with the first-ever proactive system to alert you of unwanted tracking”, which almost helped patch up the problem they created, but it only runs on Apple phones. It’s not clear what they meant by “first-ever” because hackers and researchers from the SeeMoo group at the Technical University of Darmstadt beat them to it by at least four months with the open-source AirGuard project that runs on the other 75% of phones out there.

Along the way, the SeeMoo group also reverse engineered the AirTag system, allowing anything that can send BLE beacons to play along. This opened the door for [Fabian Bräunlein]’s ID-hopping “Find You” attack that breaks all of the tracker-detectors by using an ESP32 instead of an AirTag. His basic point is that most of the privacy guarantees that Apple is trying to make on the “Find My” system rely on criminals using unmodified AirTags, and that’s not very likely.

To be fair, Apple can’t win here. They want to build a tracking network where only the good people do the tracking. But the device can’t tell if you’re looking for your misplaced keys or stalking a swimsuit model. It can’t tell if you’re silencing it because you don’t want it beeping around your dog’s neck while you’re away at work, or because you’ve planted it on a luxury car that you’d like to lift when its owners are away. There’s no technological solution for that fundamental problem.

But hackers are patching up the holes they can, and making the other holes visible, so that we can at least have a reasonable discussion about the tech’s tradeoffs. Apple seems content to have naively opened up a Pandora’s box of privacy violation. Somehow it’s up to us to figure out a way to close it.

This Mostly 3D-Printed Discone Antenna Is Ready For Broadband Duty

May 29, 2018 by Dan Maloney 16 Comments

For hams and other radio enthusiasts, the best part of the hobby is often designing antennas. Part black magic, part hard science, and part engineering, antenna design is an art. And while the expression of that art often ends up boiling down to pieces of wire cut to the correct length, some antennas have a little more going on in the aesthetics department.

Take the discone antenna, for example. Originally designed as a broadband antenna to sprout from aircraft fuselages, the discone has found a niche with public service radio listeners. But with a disk stuck to the top of a cone, the antennas have been a little hard to homebrew, at least until [ByTechLab] released this mostly 3D-printed discone. A quick look at the finished product, resembling a sweater drying rack more than a disc on top of a cone, reveals that the two shapes can be approximated by individual elements instead of solid surfaces. This is the way most practical discones are built, and [ByTechLab]’s Thingiverse page has the files needed to print the parts needed to properly orient the elements, which are just 6-mm aluminum rods. The printed hub pieces sandwich a copper plate to tie the elements together electrically while providing a feedpoint for the antenna as well as a sturdy place to mount it outdoors. This differs quite a bit from the last 3D-printed discone we featured, which used the solid geometry and was geared more for indoor use.

Interested in other antenna designs? Who can blame you? Check out the theory behind the Yagi-Uda beam antenna, or how to turn junk into a WiFi dish antenna.

[via RTL-SDR.com]

Ham Radio Public Service Activities – Rewarding And Useful

January 15, 2016 by Rud Merriam 19 Comments

“Hi! I’m Rud, Kilo Five Romeo Uniform Delta.” That’s me introducing myself at a ham meeting. Ham radio operators kid that we don’t have last names, we have call signs.

Becoming an Amateur Radio Operator (ARO), our more formal name, is not difficult and opens a world of interesting activities, including hacking. As with anything new, becoming actively involved with an existing club can be daunting. The other hams at a meeting are catching up with their buddies and often seem uninterested in the new guy standing nearby. Some groups will invite new members to stand and introduce themselves early in the meeting, which helps break the ice.

Regardless of how anyone else acts at the meeting there is one ham who is always looking for someone new – the ham who manages public service events, where amateur radio operators help establish communications for large public gatherings. These can be local bike rides, walks, or runs; I’ve even seen hams working an art show. In the nomenclature adopted since 9/11, these are “planned incidents” in contrast to “unplanned incidents” like hurricanes, tornadoes, forest fires, snow storms, and other natural or man made disasters. Working planned incidents is training for unplanned incidents when that need arises. The basic activities for AROs are the same.

Here in the Houston there are two very big events that enlist hundreds of hams. The big one in January is the Houston Marathon. The other large event is the Houston to Austin Multiple Sclerosis 150 (MS 150) mile bike ride in April. That event starts on Saturday morning, takes a break mid-way on Saturday evening, and finally wraps up late on Sunday evening. Starting in the fall there are warm-up events for the Marathon and in the late winter bike rides to prepare riders for the MS-150. There are also other marathons, Iron Man races, walks, runs, and races throughout the year. Wherever your are, there are probably events nearby and they can always make use of your radio capability.