[kabdib]

I'm imagining a "stealth" wifi controller on one of the custom chips, hung onto a pin connected to an internal antenna realized on an internal copper layer of the motherboard. If you used a non-standard frequency and protocol, who would know?

You could probably get an okay transmit-only signal with fairly unremarkable on-chip hardware (say, a simple PCM) and something that didn't look too much like an antenna even if you X-ray'd the board. I'm guessing that a similarly stealthy receiver would be noticeable due to required external discrete components (e.g., amplifiers, filter networks).

Plonking down a whole chip for "secret wifi" is likely overkill.

[jws]

…something that didn't look too much like an antenna…

The Raspberry Pi Zero W has a perfectly serviceable antenna which is simply a cavity formed between layers of copper and two tiny capacitors which look about like grains of salt.

You can read more at https://www.raspberrypi.org/magpi/pi-zero-w-wireless-antenna...

They are designed by some very clever Swedes. http://www.proant.se/en/news.htm

That second page shows the Raspberry Pi 3B+ whose antenna looks to be just a trace with the aforementioned grains of salt on it.

[monochromatic]

Antenna design is total black magic. Intuition is useless here.

[Kliment]

Antenna design is not black magic. There are a few well-understood basic patterns and you parametrize those. Some of those look quite exciting and tuning the matching network is annoying if you've never done it before but typically you use a template for an antenna design and set the parameters to what gets you best simulation results, then prototype and measure and set the matching network to match your measurements. It's not magic, it's normal everyday engineering.

Coming up with new fundamental antenna designs feels a bit black magicky to us lowly electronics people, but that's just because it's more applied physics than engineering. Here's an example of how new antenna pattern design is done: http://sci-hub.tw/https://www.sciencedirect.com/science/arti...

[mmagin]

No it's not, it just seems that way to the vast majority of us who haven't developed the proper intuition.

[wallflower]

Of course, there is the GA evolved antenna.

https://en.wikipedia.org/wiki/Evolved_antenna

[Terr_]

Slightly related, an FPGA circuit designed by a genetic algorithm which ended working due to analogue effects and hardware-specific magnetic flux interference.

https://www.damninteresting.com/on-the-origin-of-circuits/

[Bromskloss]

It makes you wonder if it would be useful to create a programmable circuit where such analogue effects are the intended working principle.

[tim333]

And the 'thing' device http://www.cryptomuseum.com/covert/bugs/thing/index.htm

[WhitneyLand]

For this or other successful genetic algorithms, it would seem clear you still can’t know if it’s an optimal design simply because in most cases the number of designs tested would be a small fraction of the possible designs.

However, things like useful sound recognition being done with only a small number of logic gates (commenter below provided a nice article, thank you) make it hard to imagine doing much better.

I wonder if the process can be shown theoretically to offer any help in guaranteeing minimum bounds w.r.t. the optimal case, even if can’t be fully proven to be optimal.

[shawn]

The NSA developed their own networking protocol, separate from TCP or UDP, which operates just above the physical layer.

The idea is that you rewrite the network card firmware so that there’s an NSA MITM running on it. The host computer never knows, because as far as the computer is concerned the network card is sending exactly the data you would expect. And even if you hook up network monitoring tools externally, you wouldn’t be able to notice anything wrong apart from a slightly reduced total bandwidth.

The value of such a tool is that it can be installed remotely, with no physical presence.

They also have all kinds of gadgets to defeat airgaps. IIRC one of them was a replacement keyboard that looks identical to the normal one, but provides the stealth wifi you mention.

One way to get an idea of what the NSA is up to is to look at their job listings. They can fake everything else, but not those.

[Cyph0n]

> which operates just above the physical layer.

So at the link layer? If so, what you described does not sound like an effective technique to exfiltrate data over the internet, unless the NSA also controls the LAN/internal network the target device is on.

Why? Because any non-standard protocol data will be thrown out by the first switch or router on the path out of the target LAN. In other words, the exfiltrated data will not be forwarded on to the next router or switch, simply because the next router/switch will not have support for the NSA's custom protocol in its network stack.

[nickpsecurity]

"Why? Because any non-standard protocol data will be thrown out by the first switch or router on the path out of the target LAN. "

That's not necessarily true. Misconfigurations and weird issues in networking gear caused vendors to be kind of permissive about some things. Depending on the vendor, they might drop it or pass it through. Network security folks in the field, in or away from NSA, probably have a good idea of what things make it through most often plus fall-back options. They might even keep current documentation of it based on field reports over time. They'd just use that stuff. Also, intelligence work is very difficult and opportunistic already. A method doesn't have to work all the time: just enough to keep trying it.

[shawn]

One thing the NSA is very good at is getting access to virtually every type of networking card. If they achieve access to a target, it's likely they control a path to it.

If the target is a wifi device, the custom protocol becomes doubly effective: Exfiltration is a matter of having a receiver anywhere in the vicinity. And that receiver can amplify the signal to blast it a few miles. There are tools to sweep the EM spectrum looking for anomalies like this, but they seem to be rare, for the moment.

[viraptor]

> If they achieve access to a target, it's likely they control a path to it.

Without specific, documented cases this is speculation of course. But I don't see why they'd use a link level protocol. 1. It requires patching multiple networking devices in the path, which is not very quiet. 2. It sticks out in any monitoring (via mirror ports) more than a UDP packet to a random host. DNS or ntp as a transport would be much simpler to hide.

[amoshi]

And what exactly would be the problem for the NSA with patching networking devices? They even mention how it's useful specifically for these hard targets

>"some of the most productive operations in TAO because they pre-position access points into hard target networks around the world."

https://arstechnica.com/tech-policy/2014/05/photos-of-an-nsa...

[Bromskloss]

Could packet delays perhaps survive over the network?

[nickpsecurity]

Yes. I used both header fields and delays as covert channels in the past since I know security professionals never looked for them. I derived them by just applying a standard, covert-channel analysis on the protocol. Others have described some methods publicly:

https://defcon.org/images/defcon-10/dc-10-presentations/dc10...

https://engineering.purdue.edu/dcsl/publications/papers/2009...

The oldest methods of finding stuff like this are Kemmerer's Shared Resource Matrix (1983) for storage channels and Wray's updated characterization (1991) that were used in DOD's security certification (TCSEC). They work for hardware, too, since it's how they found cache-based, timing channels in hardware hosting the VAX Security Kernel in 1992.

http://www.cs.ucsb.edu/~sherwood/cs290/papers/covert-kemmere...

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.534....

For transport, military-grade security often mandated fixed-size, fixed-rate transmission with error handling itself not able to leak stuff. Tricky on error part, inefficient other part. A primitive software defense is to clear the storage channels while throttling and randomizing the timing of delivery. Works best on non-real-time or already-slow configurations. Idea fit for store-and-forward messaging, which was preferred for high-assurance security. Another option from 1990's high security was to have a PCI card or something running a security kernel do the actual transfer from a labeled source. As in, the source can be as malicious as it wants with it unlikely to effect secure kernel. The kernel might prevent it, detect it, shut it down, or preserve logs for traceability. There was also the "force everything over link/network encryptor" concept to attempt to cheat. Leaves some metadata which can be mitigated or obfuscated by other means including prior transmission method.

Hope that helps. Current work uses models or languages to track shared resources for automatically detecting storage or timing channels among other things. I'll dig some out of my collection if anyone wants them.

[artificial]

Interesting, please share when you’ve the time. Thanks!

[nickpsecurity]

Language-based Information Flow Security (2003)

http://www.cs.cornell.edu/andru/papers/jsac/sm-jsac03.pdf

Note: This is a great overview with plenty of terms you can use to find modern work. It's branching out in all these areas. Key words to use include "non-interference", "static analysis," "covert channels," "labels," "confidentiality," and "side channels."

Securing Information Flow at Runtime (2008)

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.142....

Note: Example of the language work they do to lay down foundations.

Static, Info-Flow Analysis That Handles Implicit Flows (2010)

http://www.cs.rpi.edu/~milanova/docs/csmr10.pdf

Note: This is a bit more like how you'd develop low-intervention, preventative analysis.

Static, Info-Flow Analysis on Hardware Language (2017)

https://www.cs.cornell.edu/andru/papers/trustzone/asplos17.p...

SecVerilog: Security-Typed HDL for Secure Hardware without Runtime Components (2017)

https://people.ece.cornell.edu/af433/pdf/ferraiuolo-dac-17.p...

Inline, Information-Flow Monitor for JIT-like Applications

https://www.cs.stevens.edu/~naumann/inlining/Chudnov_Informa...

Jif, Sif, and Fabric

https://www.cs.cornell.edu/jif/

Note: Used in Civitas secure voting app. Links to Sif and Fabric are down the page a bit. Note 2: You should be noticing by now that the Cornell teams (a) are pretty awesome and (b) were way ahead of most on this stuff.

Deterministically Deterring Timing Attacks in Deterland (2016)

https://pdfs.semanticscholar.org/6aa3/18e95cae5a932e330857e5...

Note: Thanks to a few events, there are piles of work on hardware ranging from invididual components to whole chips. So, I'm just grabbing examples of different types. This one is on VM's in cloud.

Øzone: Efficient Execution with Zero Timing Leakage for Modern Microarchitectures (2017)

https://arxiv.org/pdf/1703.07706.pdf

Note: Dedicated, execution unit.

SAFE processor

http://www.crash-safe.org/papers.html

Note: Its metadata engine can do secrecy labels. It can do a lot of policies actually. Commercially available for RISC processors as CoreGuard.

Software-based, Gate-level Information Flow Security for IoT Systems (2017)

http://rakeshk.crhc.illinois.edu/micro17_cam.pdf

Note: Throwing an attempt in that's trying to avoid secure processors. Only read abstract since I just found it. I'm always skeptical if commodity chips are involved, though. Best I've seen are hardware I.P. that reuse optimized processors sort of sitting between their cores and the decoders or RAM. Plus, multicore without shared caches or multiprocessing with each core/chip a security domain.

So, there's some different things for you. Kemmerer and Wray are definitive, older works. Sabelfield and Myers best overview of new stuff. After Meltdown/Spectre, the rest is coming so fast I'm not even tracking it. I'm glad someone asked justifying an attempt at a survey. Found some good links. :)

[jsjohnst]

It’s comments like yours why I always check the thread after reading an article. Thank you!!

[nickpsecurity]

Comments like yours keep me writing them. Thank you! :)

[cozzyd]

Why wouldn't an organization fake their job postings to lead people astray? Like if the FSB started hiring string theorists or telekinesthetics positions to waste the NSA's time figuring out why they're doing that.

[defen]

> Like if the FSB started hiring string theorists or telekinesthetics positions to waste the NSA's time figuring out why they're doing that.

They already did that: https://www.atlasobscura.com/articles/nikolai-khokhlov-kgb-p...

[fooker]

Do you have a source for this claim?

[secfirstmd]

Exactly my question!

[jonhendry18]

" They can fake everything else, but not those."

They could hire through front companies, obfuscating the connection to the NSA.

[secfirstmd]

Interesting....source?

[01100011]

You could put the whole thing in a faraday cage and look at the emissions with a spectrum analyzer. There's probably a bunch of wide spectrum noise though, thanks to all those squarewaves running at various frequencies. If you were smart, you might try modulating one of those signals(sort of like the 'spread-spectrum' feature of many BIOSes, but with information doing the modulation and not just noise). You might be able to sneak other signals in amongst all the noise. Hell, spread spectrum signals can sit below the noise floor... I don't really think there's a way you could be 100% certain that the laptop wasn't exfiltrating data.

[meredydd]

Transmitting radio waves with a spread-spectrum CPU clock, you say?

Here's a project to turn the Raspberry Pi into an FM radio transmitter using this exact trick:

http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspb...

[cesarb]

You could use an already existing wire as an antenna. For instance, many cell phones use the headphone wire as the antenna to receive digital TV.

On a laptop, there are several wires long enough to be used as an antenna. For an obvious example relevant to this article, the wires for the camera.