[HN Gopher] Receiving unintentional voice transmissions from GPS...
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Receiving unintentional voice transmissions from GPS satellites
Author : thcipriani
Score : 120 points
Date : 2023-07-15 17:49 UTC (5 hours ago)
(HTM) web link (www.rtl-sdr.com)
(TXT) w3m dump (www.rtl-sdr.com)
| 1letterunixname wrote:
| And possibly intentional misuse for criminal and perhaps non-
| criminal activity too.
|
| 121.5 and 243 MHz are no longer officially monitored for voice
| distress signals, but I wonder if they're still being gathered on
| the fleet.
|
| Perhaps the best mitigation, I suppose a reduced set of these
| signals are monitored for voice distress calls. The satellites
| should support geofenced/location-selective rejection of signals
| on 406 MHz and 1544.2 MHz identified as non-emergency traffic to
| prevent misuse by pirates, drugs dealers, and warlords
| coordinating attacks.
| jcrawfordor wrote:
| What you're proposing is an enormous increase in complexity of
| equipment, which would have an impact not only on price but
| also reliability of the space segment. A "bent-pipe" space
| segment with minimal control logic is a well-established norm
| in communications satellites for a few reasons, ranging from
| reliability to making it possible to use existing transponders
| with future modes. Even still, more and more communications
| satellites use digital transponders that can authenticate
| source messages, and so this issue mostly exists with legacy
| satellites that can't be retrofitted.
|
| Besides, there's not really much motivation to mitigate this
| problem. First, pirate satellite communications by SARSAT
| transponders are rare compared to other satellite systems very
| popular with pirates like legacy US Navy communications
| satellites. Second, satellite piracy isn't that popular
| overall. Mitigating the ability of criminal organizations to
| communicate this way would require taking down a lot of
| different satellite systems, and then they would just fall back
| to HF radio, which is already the more popular approach. It's
| doubtful there would be any major reductions in crime and the
| type of crime that seems to motivate the most use of satellite
| piracy---unlicensed fishing near the Phillipines---isn't super
| high on the list of international priorities.
| dweekly wrote:
| What is your basis for a claim that 121.5 (guard) is
| unmonitored?
|
| As a pilot I can say that claim is false - guard is very
| actively monitored everywhere in the United States. Were you
| referring to some other locations?
| jcrawfordor wrote:
| COSPAS-SARSAT no longer monitors 121.5, for various reasons,
| so no satellite systems regularly monitor 121.5. This means
| that 121.5-only ELTs are obsolete, and prohibited for
| installation by the FAA since 2018. Modern ELTs are COSPAS-
| SARSAT transponders like EPIRBs and PLBs with only minor
| aviation-specific features.
|
| ATC does still monitor 121.5, but that's with an eye towards
| voice transmissions, not radio beacon activations. COSPAS-
| SARSAT has never carried voice traffic on 121.5, the
| satellites attempted onboard Doppler direction finding of the
| beacon tone (not very accurate at all, one of the reasons it
| is obsolete). At the same time, ATC no longer has RDF
| capability from most (all?) GATRs, so receiving the ELT
| beacon tone is mostly useless to ATC, and ATC is unlikely to
| receive it anyway since GATRs have very poor coverage down to
| ground. ELTs do still transmit on 121.5 for convenience of
| search aircraft, but it's becoming increasingly irrelevant
| with high COSPAS-SARSAT coverage (if the ELT activated at
| all, rescue coordinators already know the location by GPS
| coordinates) and increasing rarity of direction finding
| equipment (and pilot experience with RDF) on aircraft.
|
| One way to sum it up is this: 121.5 is monitored for distress
| calls from aircraft in the air, but it is _not_ monitored for
| distress calls from aircraft on the ground. The latter is the
| goal of search and rescue systems, and the use of 121.5 has
| been replaced by the much more modern COSPAS-SARSAT system
| originally developed for maritime rescue.
| doctor_eval wrote:
| I had to look this up. Wow!
|
| https://en.m.wikipedia.org/wiki/International_Cospas-
| Sarsat_...
|
| > The International Cospas-Sarsat Programme is a satellite-
| aided search and rescue (SAR) initiative. It is organized
| as a treaty-based, nonprofit, intergovernmental,
| humanitarian cooperative of 45 nations and agencies (see
| infobox). It is dedicated to detecting and locating
| emergency locator radio beacons activated by persons,
| aircraft or vessels in distress, and forwarding this alert
| information to authorities that can take action for rescue.
| Member countries operate a constellation of around 66
| satellites orbiting the Earth which carry radio receivers
| capable of locating an emergency beacon anywhere on Earth
| transmitting on the Cospas-Sarsat frequency of 406 MHz.
| patrakov wrote:
| Quick summary:
|
| > Many navigational and meteorological satellites carry a search
| and rescue (SAR) repeater which is intended to receive UHF
| emergency locator beacons and rebroadcast them in the L-band or
| higher. However the repeaters appear to be picking up all sorts
| of other signals from the ground, including voice transmissions.
| somethingsaid wrote:
| Shouldn't we link to the original YouTube video? This website
| just reposts it with no analysis, a bunch of ads, and some janky
| scroll hijacking.
| superkuh wrote:
| It's text and not video. Just speaking personally I wouldn't
| have clicked on or commented on a youtube video link. rtl-
| sdr.com is pretty decent aggregator as far as hobby SDR goes
| despite their bias in promoting their custom rtl-sdr dongle.
| somethingsaid wrote:
| Yeah, I understand the preference for text, and I'm not
| against the site itself for posting it (I don't have enough
| knowledge to comment on its quality), but I think we should
| give credit where credit (and ad revenue) is due, and link to
| the original creator's work where possible.
| Retric wrote:
| In the vast majority of cases I prefer text, but in this
| specific case the video is actually useful for all the little
| details about what he's doing that aren't in this article or
| the words he's using.
|
| https://www.youtube.com/watch?v=U_pCHTeamn8
| fortran77 wrote:
| Submit the link and see if it gets voted to the front page.
| [deleted]
| runjake wrote:
| Direct link to video: https://www.youtube.com/watch?v=U_pCHTeamn8
| scrum-treats wrote:
| Alternative link to video:
| https://invidious.tiekoetter.com/watch?v=U_pCHTeamn8.
| bryancoxwell wrote:
| A fun video and well explained.
| acaloiar wrote:
| Few things evoke feelings of the early internet like intercepting
| unencrypted communications in the wild with off the shelf
| hardware and software.
|
| It's some how comforting to realize this is still possible today.
| charcircuit wrote:
| Considering how much progress that has been made in encrypting
| internet traffic radio seems painfully slow in evolving to be
| more secure.
|
| Edit: specifically radio protocols not carrying internet
| traffic
| withinboredom wrote:
| That's because there isn't a point. In order for encryption
| to work, you need to exchange keys at some point. Doing that
| half a world away is rather pointless. Doing it over the air,
| how do I know Alice won't intercept and broadcast her keys
| louder than me? Or just interfere and prevent me from sending
| keys?
|
| As we all learned in WWII, a code is better than encryption
| when you need complex PKI to achieve encryption. It's more
| flexible, and can even convey nuances not intended. Ah, sorry
| I mean a language, not a code. But still, code words and
| phrases are still a thing.
| charcircuit wrote:
| You are ignoring HTTPS allows people half a world awaywo
| exchange keys with a server and prevents other people
| follow interfering other than DoS attacks.
|
| >As we all learned in WWII, a code is better than
| encryption when you need complex PKI to achieve encryption
|
| I was never in WWII and I'm not sure what you mean by code
| as typically that's just encryption but less formalized.
| rootw0rm wrote:
| Referring to Navajo code talkers I assume...
|
| https://en.m.wikipedia.org/wiki/Code_talker
| withinboredom wrote:
| Https works because there is a destination address that
| goes to a physical network card. Over the air, there is
| no 'routing'. Alice can intercept my transmission, then
| literally, just use a more powerful radio to 'talk over
| me' with her keys. Ergo, MITM. I worked with guys in the
| military who did this for a living...
|
| Radio is like being able to packet sniff (and modify)
| packets from anywhere.
| jiggawatts wrote:
| HTTPS is secure against man in the middle attacks and
| will protect transmissions even over radio.
| withinboredom wrote:
| Yes, once you form the connection it is secure. The
| handshake is the part that isn't secure on open airwaves.
| This is how 'evil middle boxes' mitm connections from
| corporate networks.
|
| Edit to add: yes, there are CA's to sign the bits on a
| network. There is no CA for the radio, only proprietary
| ones. These can be reverse engineered, subpoenaed, or
| bought by state actors. Chances are, if you're
| broadcasting loud enough to be heard by them, they're
| going to start listening.
| uw_rob wrote:
| I think there is some confusion here. HTTPS is secure.
| Even with MITM attacks.
|
| This is because the MITM will not have a valid
| certificate to provide authenticity for the public key
| returned.
|
| The reason why middle boxes in corp networks can MITM is
| because the the corp owns the device and has installed
| their own domain trust to the device. This means the MITM
| can return a cert and public key that your device will
| trust. This is because the cert returned will be signed
| by the installed domain trust.
|
| Another way to think about why HTTPS is secure over
| radio: HTTPS is at the highest level of the OSI
| networking model. You could do HTTPS with pen and paper
| and the mail if you wanted. Think about starlink! The
| internet today is literally going over radio waves.
|
| This is likely why there isn't progress on encrypting old
| fashion radios! There is no need to encrypt old fashioned
| radios -- you'll just use internet over radio instead if
| you wanted encryption.
|
| You bring a good point through. Since it's radio, anyone
| can jam your transmissions, but, they won't be able to
| spoof your intended friend if you are using https via
| radio.
| withinboredom wrote:
| > I was never in WWII and I'm not sure what you mean by
| code
|
| I ignored this part in my original reply. I don't know if
| you're just being an ass, never paid attention in school,
| or just simply don't know through no fault of your own.
| I'm going to assume the latter.
|
| Check it out:
| https://simple.wikipedia.org/wiki/Code_talker
|
| It's pretty wild.
| niij wrote:
| I'd take it easy with the name calling. Your replies in
| this thread have shown a pretty fundamental
| misunderstanding of the OSI model, PKI, and encryption in
| general.
| fortran77 wrote:
| > In order for encryption to work, you need to exchange
| keys at some point.
|
| Not since 1976.
|
| https://en.wikipedia.org/wiki/Public-key_cryptography
| withinboredom wrote:
| You still need to exchange keys. You can't get around
| that. Otherwise, how do I know the public key you sent me
| over the radio is YOUR public key and not someone else
| with a more powerful radio?
| krisoft wrote:
| By having the key signed by someone who you trust. Which
| in a military typically means the central command.
| kelnos wrote:
| Sure, but then you need the central command's public key
| in order to verify that signature. How do you get that?
|
| Ultimately it boils down to you needing to bootstrap your
| web/chain of trust somehow. In a military it might be
| easier; radios would be distributed to field troops with
| the needed trusted keys already present.
|
| But more "public" radio? We don't have a sort of "radio
| CA", and there are no radios that know how to deal with
| such a thing. I suppose we could reuse the TLS CAs,
| though, and build SDRs to use it, which wouldn't rely on
| any particular hardware. But the point is that this just
| isn't set up at all.
| stevezsa8 wrote:
| I watched some documentary where the US were monitoring
| enemy communications but didn't know what a specific code
| word was referring to. If I recall correctly, the US staged
| a fake transmission that one of their islands had some
| issue or other... and suddenly they picked up enemy
| broadcast with the code word in question. So then the US
| knew what the code word referred to.
| Y_Y wrote:
| AF meant Midway
|
| https://www.history.navy.mil/content/dam/museums/nmas/edu
| cat...
|
| It's very easy to look these things up.
| TechBro8615 wrote:
| Aren't there FCC regulations that forbid encryption over non-
| military radio?
| mirashii wrote:
| For amateur radio, but no in general.
| tarxvf wrote:
| And it's not even actually illegal for amateur radio
| though there continues to be debate on the topic due to
| the phrasing.
|
| I do think that encryption is firmly outside of the
| amateur culture in most cases, but legality is well
| covered here: https://www.n5dux.com/ham/files/pdf/Data%20
| Encryption%20is%2...
| warble wrote:
| It's legal to encrypt as long as anyone can decrypt as I
| understand it.
| warble wrote:
| Sorry, has the means to decrypt it.
| charcircuit wrote:
| Well there are radio protocols like wifi and 5g which are
| encrypted, so I doubt it's illegal.
| ajsnigrutin wrote:
| Most of them are pretty secure, a few really old or
| intentionally open (ham radio) are not, but the rest, are
| (wifi, 5g, ...)
| mananaysiempre wrote:
| Does 5G finally use some sort of viable cryptosystem? 3G
| and below are hopeless and IIUC LTE is theoretically
| possible to secure but in practice the implementations
| suck.
| toast0 wrote:
| IIRC, LTE is mutually verified encryption. The SIM
| contains a private key for the subscriber and a public
| key for the network. I'd expect 5G to also have that.
| userbinator wrote:
| Some of those voices sound like Chinese... and I wouldn't be
| surprised if cheap walkie-talkies and the like are used over
| there, which are either actually using a frequency that gets
| picked up by these satelllites, or have poor/nonexistent
| filtering that their signal harmonics are.
| libpcap wrote:
| What did the conversation overheatd in that video say?
| OnlyMortal wrote:
| "People of Earth, your attention, please. This is Prostetnic
| Vogon Jeltz of the Galactic Hyperspace Planning Council. As you
| will no doubt be aware, the plans for development of the
| outlying regions of the Galaxy require the building of a
| hyperspatial express route through your star system. And
| regrettably, your planet is one of those scheduled for
| demolition. The process will take slightly less than two of
| your Earth minutes. Thank you."
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