10 ms·

Anonymity Is Hard

150 points by j_s 13y ago

patio11 13y ago
The adversary, Hezbollah, used access to the telephone company logs (they have those), and searched for atypical mobile phone usage patterns: Word to the wise, for people contemplating picking a nation state as the adversary for their circumvention tool programming project: see the amount of sophistication and technology involved here? Many countries routinely direct substantially more resources at, and I mean this entirely literally, killing mosquitoes.
- pa5tabear 13y ago
  Malaria kills more than half a million people every year, and mosquitoes are the primary vector. Killing mosquitoes is not trivial.
  - saturdayplace 13y ago
    Perhaps that reinforces the point even more?
  - pyre 13y ago
    ... so we should learn OpSec from mosquitoes?
    - throwaway9101 13y ago
      Breed until they can't slaughter us all!
    - saraid216 13y ago
      My instincts say that I should link Goonswarm from EVE Online at this point.
  - ballard 13y ago
    It's an interesting footnote to history that the southern US had endemic malaria prior to 1949. https://en.wikipedia.org/wiki/National_Malaria_Eradication_Program https://en.wikipedia.org/wiki/National_Malaria_Eradication_P...
j_s 13y ago
Encryption isn't enough! - an interesting lesson in [...] real world counterintelligence - they were looking for [...] the exact usage pattern [...] for a mobile that is used exclusively for a handler to contact an agent - privacy of communication content [...] is not sufficient to protect against even minimal monitoring
- smacktoward 13y ago
  It's actually worse than that. It's not just that encryption isn't enough, it's that encryption can be worse than no encryption, since using encryption marks you out as someone who's different than the vast majority of users on the network. In a world where normal people are happy to sling everything around in the clear, a person using any encryption at all flags themselves as potentially suspicious. (Not suspicious enough by itself to give a Western law enforcement agency what it needs to make a case against you -- but more than enough to convince less scrupulous actors like intelligence agencies that you're a person deserving of a hard, hard look.) Moreover, the more sophisticated the encryption you use, the more you set yourself apart from the crowd, further increasing your vulnerability.
  - mahyarm 13y ago
    This is why we want to make it standard for the world over. If everyone uses OTR chat clients, you using OTR chat clients doesn't stand out. If the corporate world uses VPN, then VPN traffic doesn't stand out. If %70 of the internet is always under SSL, then you using another SSL website or email server does not stand out. If %10 of the country uses TOR to look at porn or whatever else in your country because you restrict it with your countries' firewall, then TOR doesn't stand out.
- EGreg 13y ago
  Anonymity + One Time Pad encryption is sufficient http://pastie.org/private/fkbu4qpsvwcwiocrdeang http://pastie.org/private/fkbu4qpsvwcwiocrdeang But you have to have real anonymity! If I didn't link to the above, would you know who wrote it? Would you know what the message was?
knodi 13y ago
If I run a tor node on my home network would that raise viable defense of claim that the traffic originating from network was/could possibly not be my own?
- gwern 13y ago
  Yes. One of the investigative tools is correlating presence of a nick online with Tor activity from a suspect. IIRC, they did this on an Anonymous they were tracking a few years ago: watched his physical Internet connection, and observed that the traffic matched his IRC nick's presences.
  - pygy_ 13y ago
    To counter this kind of attack, you'd need to proxy through tor to a server, which would also connect to the rest of world through tor. You would then create a script on a local machine (say, a Raspberry Pi) that simulates traffic to the proxy while you're not active.
    - AnIrishDuck 13y ago
      Traffic analysis is still possible under this scenario. It's only marginally harder. How would your magic traffic generator work? Randomly send a packet every minute? Not good enough, it'd be very easy to detect increased activity, which would be correlated to actual usage of the Tor network. The best you could do is create some kind of Tor gateway that buffers packets. This gateway would always send n packets / minute through Tor in some programmatic pattern isolated from any packet input. If n real packets aren't available, send fake packets in their place. This is further complicated by length analysis; you would need some way to limit the length of real outgoing packets (probably via MTU) and their data so length is indistinguishable from the fakes. You should also avoid any sort of wireless connection to this gateway, as snoopers could detect this traffic from outside your residence and again break this scheme. And the whole scheme still falls apart if your adversary is willing / capable of entering your residence. Needless to say, many nation-state level adversaries are completely comfortable doing this.
jsnk 13y ago
I am the creator of Dmtri.com. It's a place where you can share thoughts anonymously whether you are signed up or not. Even when you sign up you have a choice to write anonymously to keep track of your writing. Anonymity online is really important to me and I want to learn more about how to achieve that. As a rule of thumb, I use Tor when I browse. What other things can people do to hide their trace online?
- dmix 13y ago
  OPSEC. Read more from the blog posts author (grugq). He talks about how hackers hide themselves anonymously. It's not just a technology choice, it's lifestyle changes and it's a huge commitment.
  - jsnk 13y ago
    Will do. Thanks for the referral. I actually didn't know about the lifestyle side of the story.
- grugq 13y ago
  Start with this piece "observations on OPSEC" http://grugq.tumblr.com/post/61960027685/observations-on-opsec http://grugq.tumblr.com/post/61960027685/observations-on-ops... which sets out some broad outlines of what is involved.
  - jsnk 13y ago
    Thanks for the link. Definitely will be reading that.
- pdoconnell 13y ago
  If you are working on such a site, I hope several things. 1) That the user name you're using here is randomly generated 2) You used domain registration authorities that consider secrecy imperative. Even with that, you used single-use credit cards or the like, and didn't use your real name. 3) You always browse everything in whatever your browser's privacy mode is. It doesn't solve everything, but its another layer. 4) Do not have java or flash installed, it can expose you more and leak data. 5) Finally, really do not go to sites like this and ask questions like this without having a burner account set up. If you have to ask these questions, log in from a location you will never visit again. Use a tool like the trashmail extension to use one-of accounts (https://addons.mozilla.org/En-us/firefox/addon/trashmailnet/ https://addons.mozilla.org/En-us/firefox/addon/trashmailnet/)
peterwwillis 13y ago
Organized criminals seem a lot better at keeping their operations and methods hidden than the CIA. Perhaps the CIA should do some case studies?
Edvik 13y ago
This is the exact way in which metadata, in the age of computer analysis, is just as important as the data itself. With a computer looking for patterns, it's possible to sift through billions of pieces of data to single out someone trying to hide in the noise.
avty 13y ago
It's a startup opportunity.
cs702 13y ago
Key insight: "The problem with many security systems based purely on secrecy is that their usage is itself anomalous. It singles out and attracts attention to the users." In other words, the very use of secrecy is itself a weakness that can be exploited by attackers.
- wyck 13y ago
  The espionage game has always been about being clandestine, many new techniques attract attention (tor for example) because of their honeypot nature. The old adage of hiding in the crowd will always be more difficult to notice.
  - rdtsc 13y ago
    Is steganography then something that should be used? "I just like looking at pictures of cats on imgur" (while they actually contain handler's instructions). Now is a 40 year old Syrian man looking at pictures of cats on imgur?. That's anomalous. I guess one can't hide the need for a human factor, in other words tailoring it for a particular case. It used to be that spies had short wave radios. You know they still have stations for example. http://en.wikipedia.org/wiki/Numbers_station http://en.wikipedia.org/wiki/Numbers_station That's pretty good. Well except that this day and age spotting someone with a shortwave radio who is already a bit suspicious (maybe doesn't speak with the correct accent) is going to raise eyebrows perhaps. While maybe 10-30 years ago it wouldn't have. So...now twitter is used for number stations: http://boingboing.net/2013/03/11/numbers-stations-on-twitter-an.html http://boingboing.net/2013/03/11/numbers-stations-on-twitter... Except that it is suspicious to access it and so on. In other words it is a hard task not to be suspicious.
    - conductor 13y ago
      > Now is a 40 year old Syrian man looking at pictures of cats on imgur?. That's anomalous. Hide in porn, watching porn is not suspicious.
      - rdtsc 13y ago
theboywho 13y ago
I think this is not exactly about anonymity and the title is a little bit misleading. The title should be "Hiding secret activities is hard", as anonymity also applies to cases where you have nothing to hide.
- morley 13y ago
  You seem overly concerned with adding your political feelings to the concept of anonymity. One definition of anonymity is "lacking individuality, unique character, or distinction," which is what spies attempt to do when they practice tradecraft. This article is about how difficult it was to do that. While I do think the title lacks specificity to the topic, I don't think it's incorrect or misleading.
  - theboywho 13y ago
    > You seem overly concerned with adding your political feelings to the concept of anonymity. What makes you think those are "political" "feelings"? > While I do think the title lacks specificity to the topic, I don't think it's incorrect or misleading. I just changed my mind and I think the same thing as you do.
    - grugq 13y ago
      As it states in the opening paragraph, the post prompted as a response to this blog post: http://blog.cryptographyengineering.com/2013/03/here-come-encryption-apps.html http://blog.cryptographyengineering.com/2013/03/here-come-en... > It seems like these days I can't eat breakfast without reading about some new encryption app that will (supposedly) revolutionize our communications -- while making tyrannical regimes fall like cheap confetti. The point that my post was driving at is that simply having a great usable and secure encrypted chat application is meaningless in the face of a nation state adversary. The resources that they have available, and the approach that they take to unmasking people is not dependant on being able to read the content of their messages. Using "Super Crypto Chat 5000" to protect your message content doesn't buy you anything if you're the only person using it, and you have access to information that would place you in a pool of suspects. As we're now seeing with the Snowden documents, this is exactly how the national security forces see encrypted messages. They pay more attention to them, and they look at who is sending them to whom. Finally, while a more accurate title might be "Clandestine Operative Tradecraft is Complex and Error Prone in the Face of Nation State Level Adversaries" that isn't really pithy. of course they want to read the messages and it helps them tremendously, that isn't necessary for them to be effective as a security force.
conductor 13y ago
One solution (if you really need to communicate using a mobile phone) is to drive (better with public transport or in taxi) with the phone (turned off, no battery) to some random location, with no CCTVs around, turn it on at predefined time, wait for contact, turn it off, remove the battery, go home. The phone must be clean (not used before with other SIM cards that can be linked to you) and the SIM card must be clean (not used with other phones that can be linked to you). And you should change the phone (or at least its IMEI, but better change the phone, changing the IMEIs is illegal in most countries) and the SIM card regularly. Edit: Or better use the internet for communications, cryptography and steganography are working.
- eksith 13y ago
  All invalidated by corroborating the times with the call log where you were not present. Your edit is a better option in that regard, but as long as online is blended in some way with offline, anonymity is impossible... which is why I don't even bother for the most part.
  - userulluipeste 13y ago
    If you don't have much of a presence (either social or on-line) to begin with, like being a reserved person, there isn't much data to be corroborated with in the first place.
    - eksith 13y ago
      True. But then again, you don't need that much anyway. I doubt they scanned his entire email archive at least first. Just the fact of including his real email and that one post on SO seemed to have been enough to establish probable cause. His social interactions could have only been directly traced to 2-3 posts outside of Tor at most. What really did him in are the pseudonyms and similarity of preferences picked up from those few instances. So really, any online/social presence is a liability if it's contaminated with something about you offline.
- grugq 13y ago
gwright 13y ago
This is an example of a very old tactic, traffic analysis.
sciguy77 13y ago
Why didn't they use satellite phones? Seems like that would bypass the whole phone logs issue.
- smacktoward 13y ago
  My guess would be deniability. If the Bad Guys come search your house and you have a mobile phone sitting in a drawer, that in itself isn't incriminating, because lots of people have mobile phones sitting in drawers. Very few people have satphones sitting in drawers, though, so possessing one would be anomalous -- which raises suspicions in the same way that having a mobile phone that never moves and only infrequently turns on does.
- rmc 13y ago
  Firstly, I'm pretty sure they leave phone logs anyways, just not with the local teleco. Secondly, you're going to look suspicous with a satillite phone when everyone else has a mobile, and I doubt you can buy prepaid satillite phones with cash and non documentation like you can with mobile phones.
- liotier 13y ago
  What makes you believe that satellite phones are not operated by companies that keep logs and pass them along to their local lord ?
mkup 13y ago
The adversary, Hezbollah, used access to the telephone company logs (they have those), and searched for atypical mobile phone usage patterns. Very important observation for advocates of two-factor authentication: cellular network and SMS services in some parts of the world are not trustworthy. It's much better to use single strong password versus weak password + numeric codes delivered by SMS which can be monitored/changed on the fly by an adversary.
- EGreg 13y ago
  What the CIA should have done is have phones which impersonate actual, "normal" phones when necessary and send messages which resemble normal messages. Not "PIZZA!" but whatever the local people send, e.g. "miss u". There could be a challenge-response that is not deterministic, e.g. "are we still on for tomorrow?" "looking forward to it" and then some normal sounding conversation (of course, tomorrow wouldn't be the day they would meet). The key is to impersonate enough phones (tunneling over a trusted subset of the network) or use a network that won't identify the endpoints. The former is much easier.
  - mkup 13y ago
    They could even transfer usual "miss u"-alike stuff over SMS, and encode actual message in the time delays.
    - EGreg 13y ago
      Great point! Anyway they don't even have to use SMS. Anonymity is easy: http://pastie.org/private/fkbu4qpsvwcwiocrdeang http://pastie.org/private/fkbu4qpsvwcwiocrdeang Would you know who wrote it if I didn't link to it?
      - grugq 13y ago
        If you wrote and posted it from inside Lebanon, then Hezbollah would know. Nationstate adversaries are very powerful beasts.
EGreg 13y ago
Let's be clear here. Anonymity can be maintained even if the pattern of communication is not "normal". What you need for anonymity is for the parts of the system(s) you interact with to not identify you. This certainly should apply to the nodes you interact with directly, so they should be under your control (e.g. the user-agent software, the computer you use, the facility the computer is located in, etc.) Further out, the system components have to not have a centralized ID of the endpoints. Cellphone networks DO have a centralized hub, namely the cellphone company. The key to anonymity is to make sure that none of the parts of the system can identify you, either because they don't require a centralized ID, or because the ID provider / facility / computer you used to access the system is unwilling or unable to identify you. The way that governments and other organizations combat anonymity is by requiring various systems to identify other parts of the system (e.g. cellphones) with unique identifiers before letting them use that system. There are only two ways to defeat this: 1) Create a fake user-agent, to impersonate existing identifier(s), or 2) Circumvent the requirement to identify oneself. The first one will put individuals you impersonate at risk, but it is likely they'll be let go and not subjected to "rubberhose cryptanalysis". The second one will eventually attract the attention of the governments. If they can set things up in such a way that systems (e.g. Lavabit) that refuse to identify individuals are somehow punished, their license to operate revoked, etc. then this should prove a deterrent to anonymity. In the real world there are plenty of systems in the world who do not care about who is sending the data through the wires (net neutrality is related). Some of them are tunneled over other systems. Tor is an example, Freenet is another. They use primarily legitimate, identified accounts (e.g. someone in their home using an ISP) to transmit this tunneled information, sometimes over a protocol that is indistinguishable from TLS. As long as things like SSL and TLS are allowed, this will be possible. As long as such a system is distributed enough that it doesn't have a central way to shut it down, it will be infeasible for governments to intimidate enough operators of the system into shutting it down. These are the ways to have true anonymity. PerfectDark and Freenet are used in countries with oppressive governments. Note that you can have a consistent identity and still be anonymous! This can be great for reputations, e.g. of app developers, app stores, antivirus companies and reviewers of software. I have written a lot more on the subject here: http://magarshak.com/blog/?p=114 http://magarshak.com/blog/?p=114 What the article describes is that steganography is hard. Acting in the real world while avoiding suspicion of a government with access to many systems (telephone systems, etc.) is hard. Which is probably a good thing. Terrorism is a problem of technology. 300 years ago it was nearly impossible for a few guys to kill thousands -- they'd be apprehended and stopped first. Today, there is more and more technology that empowers individuals to kill may people. This goes back to the machine-gun debate, but basically as capabilities grow (3d printers printing guns, for instance) so does the surveillance. Sadly the surveillance isn't going away, because the technology for both is only increasing.
joe_the_user 13y ago
The methods supposedly used by the CIA here seem terrible for the reasons mentioned (especially always meeting at the same pizza place). My knowledge of intelligence comes mostly from old movies but it still feels like I could have thought of something better. My guess is the methods were really simple just to keep people from screwing it up, that the thing about complicated methods is that they fall apart from people forgetting all the complicated schemes and so they're worse than simple methods (sometimes). But that's just a guess, anyone know?
ballard 13y ago
Suppose to ensure anonymity, let's call a hypothetical anonymous, encrypted mixnet overlay service : Cone of Silence. CoS has two types of N nodes: relays R and clients C (Csrc wants to send packets to Cdst). Every nodes, N, talks to each other at constant rate B. Directional asymmetric rates are allowed. If there is nothing to send, a packet containing the output of a CSPRNG must be sent to meet B, which will be dropped by the other node. Every link in each direction maintains B. C must use at least 1 node to talk to each other. Direct C-C traffic and network loops are expressly forbidden. C must agree to encrypt the contents of their opaque application payload, P, amongst themselves. R informs Csrc of the list keys (k0, k1, .. kn) to recursively encrypt P with, resulting in payload to send, M = E(kn,..E(k1,E(k0,P))). Keys must never be reused except given the same Csrc to Cdest, but only for a maximum time and number of bytes. M is decrypted by each node and forwarded on to the neighbor if it is a valid packet. N must never know the complete path a beyond the neighbor node with which to send a packet and the specified path nodes. N must be assumed to be hostile. -- The reason for russian dolls encryption per link is to prevent correlation analysis. Lots of unanswered Q's: - Node discovery / reachability - Node impersonation (remember tcp connection hijacking?) - Hostile nodes (relays and clients), especially hostile relays that prefer to connect to each other. Perhaps clients (Csrc and Cdest) each specify a small # of nodes that a path must traverse. Periodically check with each specified node with a challenge to verify path integrity? (There must be a better way to ensure path integrity using crypto without backchannels to specified nodes.) - (D|)DoS - limits for all operations. Exponential backoff. - Crypto specifics, key scheduling, rotation, minimum&maximum rekey rate. - Packet particulars (packet size tradeoff: overhead vs. latency), transport/s (TCP sounds easiest), reconnection. - Multipath? Just say no (at least initially). - How is this better than tor? (Statistical analysis may prove if a host belongs to CoS, but not to whom. Tor may not be sufficiently mixed under "capture everything".) - Node identifier? 384-bits is plenty.
kbart 13y ago
I see the only lesson here: NEVER use cell phones for activities that you want to keep secret. They are known to be easily trackable and heavily backdored. Linux netbook (single-use&destroy for extra credits) with TOR + encrypted mail or IM on public WiFi networks would be much more secure and not so impractical on such high stakes.

150 points by j_s 13y ago

The adversary, Hezbollah, used access to the telephone company logs (they have those), and searched for atypical mobile phone usage patterns: Word to the wise, for people contemplating picking a nation state as the adversary for their circumvention tool programming project: see the amount of sophistication and technology involved here? Many countries routinely direct substantially more resources at, and I mean this entirely literally, killing mosquitoes.

pa5tabear 13y ago
Malaria kills more than half a million people every year, and mosquitoes are the primary vector. Killing mosquitoes is not trivial.
- saturdayplace 13y ago
  Perhaps that reinforces the point even more?
- pyre 13y ago
  ... so we should learn OpSec from mosquitoes?
  - throwaway9101 13y ago
    Breed until they can't slaughter us all!
  - saraid216 13y ago
    My instincts say that I should link Goonswarm from EVE Online at this point.
- ballard 13y ago
  It's an interesting footnote to history that the southern US had endemic malaria prior to 1949. https://en.wikipedia.org/wiki/National_Malaria_Eradication_Program https://en.wikipedia.org/wiki/National_Malaria_Eradication_P...

j_s 13y ago

Encryption isn't enough! - an interesting lesson in [...] real world counterintelligence - they were looking for [...] the exact usage pattern [...] for a mobile that is used exclusively for a handler to contact an agent - privacy of communication content [...] is not sufficient to protect against even minimal monitoring

smacktoward 13y ago
It's actually worse than that. It's not just that encryption isn't enough, it's that encryption can be worse than no encryption, since using encryption marks you out as someone who's different than the vast majority of users on the network. In a world where normal people are happy to sling everything around in the clear, a person using any encryption at all flags themselves as potentially suspicious. (Not suspicious enough by itself to give a Western law enforcement agency what it needs to make a case against you -- but more than enough to convince less scrupulous actors like intelligence agencies that you're a person deserving of a hard, hard look.) Moreover, the more sophisticated the encryption you use, the more you set yourself apart from the crowd, further increasing your vulnerability.
- mahyarm 13y ago
  This is why we want to make it standard for the world over. If everyone uses OTR chat clients, you using OTR chat clients doesn't stand out. If the corporate world uses VPN, then VPN traffic doesn't stand out. If %70 of the internet is always under SSL, then you using another SSL website or email server does not stand out. If %10 of the country uses TOR to look at porn or whatever else in your country because you restrict it with your countries' firewall, then TOR doesn't stand out.
EGreg 13y ago
Anonymity + One Time Pad encryption is sufficient http://pastie.org/private/fkbu4qpsvwcwiocrdeang http://pastie.org/private/fkbu4qpsvwcwiocrdeang But you have to have real anonymity! If I didn't link to the above, would you know who wrote it? Would you know what the message was?

knodi 13y ago

If I run a tor node on my home network would that raise viable defense of claim that the traffic originating from network was/could possibly not be my own?

gwern 13y ago
Yes. One of the investigative tools is correlating presence of a nick online with Tor activity from a suspect. IIRC, they did this on an Anonymous they were tracking a few years ago: watched his physical Internet connection, and observed that the traffic matched his IRC nick's presences.
- pygy_ 13y ago
  To counter this kind of attack, you'd need to proxy through tor to a server, which would also connect to the rest of world through tor. You would then create a script on a local machine (say, a Raspberry Pi) that simulates traffic to the proxy while you're not active.
  - AnIrishDuck 13y ago
    Traffic analysis is still possible under this scenario. It's only marginally harder. How would your magic traffic generator work? Randomly send a packet every minute? Not good enough, it'd be very easy to detect increased activity, which would be correlated to actual usage of the Tor network. The best you could do is create some kind of Tor gateway that buffers packets. This gateway would always send n packets / minute through Tor in some programmatic pattern isolated from any packet input. If n real packets aren't available, send fake packets in their place. This is further complicated by length analysis; you would need some way to limit the length of real outgoing packets (probably via MTU) and their data so length is indistinguishable from the fakes. You should also avoid any sort of wireless connection to this gateway, as snoopers could detect this traffic from outside your residence and again break this scheme. And the whole scheme still falls apart if your adversary is willing / capable of entering your residence. Needless to say, many nation-state level adversaries are completely comfortable doing this.

jsnk 13y ago

I am the creator of Dmtri.com. It's a place where you can share thoughts anonymously whether you are signed up or not. Even when you sign up you have a choice to write anonymously to keep track of your writing. Anonymity online is really important to me and I want to learn more about how to achieve that. As a rule of thumb, I use Tor when I browse. What other things can people do to hide their trace online?

dmix 13y ago
OPSEC. Read more from the blog posts author (grugq). He talks about how hackers hide themselves anonymously. It's not just a technology choice, it's lifestyle changes and it's a huge commitment.
- jsnk 13y ago
  Will do. Thanks for the referral. I actually didn't know about the lifestyle side of the story.
grugq 13y ago
Start with this piece "observations on OPSEC" http://grugq.tumblr.com/post/61960027685/observations-on-opsec http://grugq.tumblr.com/post/61960027685/observations-on-ops... which sets out some broad outlines of what is involved.
- jsnk 13y ago
  Thanks for the link. Definitely will be reading that.
pdoconnell 13y ago
If you are working on such a site, I hope several things. 1) That the user name you're using here is randomly generated 2) You used domain registration authorities that consider secrecy imperative. Even with that, you used single-use credit cards or the like, and didn't use your real name. 3) You always browse everything in whatever your browser's privacy mode is. It doesn't solve everything, but its another layer. 4) Do not have java or flash installed, it can expose you more and leak data. 5) Finally, really do not go to sites like this and ask questions like this without having a burner account set up. If you have to ask these questions, log in from a location you will never visit again. Use a tool like the trashmail extension to use one-of accounts (https://addons.mozilla.org/En-us/firefox/addon/trashmailnet/ https://addons.mozilla.org/En-us/firefox/addon/trashmailnet/)

peterwwillis 13y ago

Organized criminals seem a lot better at keeping their operations and methods hidden than the CIA. Perhaps the CIA should do some case studies?

Edvik 13y ago

This is the exact way in which metadata, in the age of computer analysis, is just as important as the data itself. With a computer looking for patterns, it's possible to sift through billions of pieces of data to single out someone trying to hide in the noise.

avty 13y ago

It's a startup opportunity.

cs702 13y ago

Key insight: "The problem with many security systems based purely on secrecy is that their usage is itself anomalous. It singles out and attracts attention to the users." In other words, the very use of secrecy is itself a weakness that can be exploited by attackers.

wyck 13y ago
The espionage game has always been about being clandestine, many new techniques attract attention (tor for example) because of their honeypot nature. The old adage of hiding in the crowd will always be more difficult to notice.
- rdtsc 13y ago
  Is steganography then something that should be used? "I just like looking at pictures of cats on imgur" (while they actually contain handler's instructions). Now is a 40 year old Syrian man looking at pictures of cats on imgur?. That's anomalous. I guess one can't hide the need for a human factor, in other words tailoring it for a particular case. It used to be that spies had short wave radios. You know they still have stations for example. http://en.wikipedia.org/wiki/Numbers_station http://en.wikipedia.org/wiki/Numbers_station That's pretty good. Well except that this day and age spotting someone with a shortwave radio who is already a bit suspicious (maybe doesn't speak with the correct accent) is going to raise eyebrows perhaps. While maybe 10-30 years ago it wouldn't have. So...now twitter is used for number stations: http://boingboing.net/2013/03/11/numbers-stations-on-twitter-an.html http://boingboing.net/2013/03/11/numbers-stations-on-twitter... Except that it is suspicious to access it and so on. In other words it is a hard task not to be suspicious.
  - conductor 13y ago
    > Now is a 40 year old Syrian man looking at pictures of cats on imgur?. That's anomalous. Hide in porn, watching porn is not suspicious.
    - rdtsc 13y ago

theboywho 13y ago

I think this is not exactly about anonymity and the title is a little bit misleading. The title should be "Hiding secret activities is hard", as anonymity also applies to cases where you have nothing to hide.

morley 13y ago
You seem overly concerned with adding your political feelings to the concept of anonymity. One definition of anonymity is "lacking individuality, unique character, or distinction," which is what spies attempt to do when they practice tradecraft. This article is about how difficult it was to do that. While I do think the title lacks specificity to the topic, I don't think it's incorrect or misleading.
- theboywho 13y ago
  > You seem overly concerned with adding your political feelings to the concept of anonymity. What makes you think those are "political" "feelings"? > While I do think the title lacks specificity to the topic, I don't think it's incorrect or misleading. I just changed my mind and I think the same thing as you do.
  - grugq 13y ago
    As it states in the opening paragraph, the post prompted as a response to this blog post: http://blog.cryptographyengineering.com/2013/03/here-come-encryption-apps.html http://blog.cryptographyengineering.com/2013/03/here-come-en... > It seems like these days I can't eat breakfast without reading about some new encryption app that will (supposedly) revolutionize our communications -- while making tyrannical regimes fall like cheap confetti. The point that my post was driving at is that simply having a great usable and secure encrypted chat application is meaningless in the face of a nation state adversary. The resources that they have available, and the approach that they take to unmasking people is not dependant on being able to read the content of their messages. Using "Super Crypto Chat 5000" to protect your message content doesn't buy you anything if you're the only person using it, and you have access to information that would place you in a pool of suspects. As we're now seeing with the Snowden documents, this is exactly how the national security forces see encrypted messages. They pay more attention to them, and they look at who is sending them to whom. Finally, while a more accurate title might be "Clandestine Operative Tradecraft is Complex and Error Prone in the Face of Nation State Level Adversaries" that isn't really pithy. of course they want to read the messages and it helps them tremendously, that isn't necessary for them to be effective as a security force.

conductor 13y ago

One solution (if you really need to communicate using a mobile phone) is to drive (better with public transport or in taxi) with the phone (turned off, no battery) to some random location, with no CCTVs around, turn it on at predefined time, wait for contact, turn it off, remove the battery, go home. The phone must be clean (not used before with other SIM cards that can be linked to you) and the SIM card must be clean (not used with other phones that can be linked to you). And you should change the phone (or at least its IMEI, but better change the phone, changing the IMEIs is illegal in most countries) and the SIM card regularly. Edit: Or better use the internet for communications, cryptography and steganography are working.

eksith 13y ago
All invalidated by corroborating the times with the call log where you were not present. Your edit is a better option in that regard, but as long as online is blended in some way with offline, anonymity is impossible... which is why I don't even bother for the most part.
- userulluipeste 13y ago
  If you don't have much of a presence (either social or on-line) to begin with, like being a reserved person, there isn't much data to be corroborated with in the first place.
  - eksith 13y ago
    True. But then again, you don't need that much anyway. I doubt they scanned his entire email archive at least first. Just the fact of including his real email and that one post on SO seemed to have been enough to establish probable cause. His social interactions could have only been directly traced to 2-3 posts outside of Tor at most. What really did him in are the pseudonyms and similarity of preferences picked up from those few instances. So really, any online/social presence is a liability if it's contaminated with something about you offline.
grugq 13y ago

gwright 13y ago

This is an example of a very old tactic, traffic analysis.

sciguy77 13y ago

Why didn't they use satellite phones? Seems like that would bypass the whole phone logs issue.

smacktoward 13y ago
My guess would be deniability. If the Bad Guys come search your house and you have a mobile phone sitting in a drawer, that in itself isn't incriminating, because lots of people have mobile phones sitting in drawers. Very few people have satphones sitting in drawers, though, so possessing one would be anomalous -- which raises suspicions in the same way that having a mobile phone that never moves and only infrequently turns on does.
rmc 13y ago
Firstly, I'm pretty sure they leave phone logs anyways, just not with the local teleco. Secondly, you're going to look suspicous with a satillite phone when everyone else has a mobile, and I doubt you can buy prepaid satillite phones with cash and non documentation like you can with mobile phones.
liotier 13y ago
What makes you believe that satellite phones are not operated by companies that keep logs and pass them along to their local lord ?

mkup 13y ago

The adversary, Hezbollah, used access to the telephone company logs (they have those), and searched for atypical mobile phone usage patterns. Very important observation for advocates of two-factor authentication: cellular network and SMS services in some parts of the world are not trustworthy. It's much better to use single strong password versus weak password + numeric codes delivered by SMS which can be monitored/changed on the fly by an adversary.

EGreg 13y ago
What the CIA should have done is have phones which impersonate actual, "normal" phones when necessary and send messages which resemble normal messages. Not "PIZZA!" but whatever the local people send, e.g. "miss u". There could be a challenge-response that is not deterministic, e.g. "are we still on for tomorrow?" "looking forward to it" and then some normal sounding conversation (of course, tomorrow wouldn't be the day they would meet). The key is to impersonate enough phones (tunneling over a trusted subset of the network) or use a network that won't identify the endpoints. The former is much easier.
- mkup 13y ago
  They could even transfer usual "miss u"-alike stuff over SMS, and encode actual message in the time delays.
  - EGreg 13y ago
    Great point! Anyway they don't even have to use SMS. Anonymity is easy: http://pastie.org/private/fkbu4qpsvwcwiocrdeang http://pastie.org/private/fkbu4qpsvwcwiocrdeang Would you know who wrote it if I didn't link to it?
    - grugq 13y ago
      If you wrote and posted it from inside Lebanon, then Hezbollah would know. Nationstate adversaries are very powerful beasts.

EGreg 13y ago

Let's be clear here. Anonymity can be maintained even if the pattern of communication is not "normal". What you need for anonymity is for the parts of the system(s) you interact with to not identify you. This certainly should apply to the nodes you interact with directly, so they should be under your control (e.g. the user-agent software, the computer you use, the facility the computer is located in, etc.) Further out, the system components have to not have a centralized ID of the endpoints. Cellphone networks DO have a centralized hub, namely the cellphone company. The key to anonymity is to make sure that none of the parts of the system can identify you, either because they don't require a centralized ID, or because the ID provider / facility / computer you used to access the system is unwilling or unable to identify you. The way that governments and other organizations combat anonymity is by requiring various systems to identify other parts of the system (e.g. cellphones) with unique identifiers before letting them use that system. There are only two ways to defeat this: 1) Create a fake user-agent, to impersonate existing identifier(s), or 2) Circumvent the requirement to identify oneself. The first one will put individuals you impersonate at risk, but it is likely they'll be let go and not subjected to "rubberhose cryptanalysis". The second one will eventually attract the attention of the governments. If they can set things up in such a way that systems (e.g. Lavabit) that refuse to identify individuals are somehow punished, their license to operate revoked, etc. then this should prove a deterrent to anonymity. In the real world there are plenty of systems in the world who do not care about who is sending the data through the wires (net neutrality is related). Some of them are tunneled over other systems. Tor is an example, Freenet is another. They use primarily legitimate, identified accounts (e.g. someone in their home using an ISP) to transmit this tunneled information, sometimes over a protocol that is indistinguishable from TLS. As long as things like SSL and TLS are allowed, this will be possible. As long as such a system is distributed enough that it doesn't have a central way to shut it down, it will be infeasible for governments to intimidate enough operators of the system into shutting it down. These are the ways to have true anonymity. PerfectDark and Freenet are used in countries with oppressive governments. Note that you can have a consistent identity and still be anonymous! This can be great for reputations, e.g. of app developers, app stores, antivirus companies and reviewers of software. I have written a lot more on the subject here: http://magarshak.com/blog/?p=114 http://magarshak.com/blog/?p=114 What the article describes is that steganography is hard. Acting in the real world while avoiding suspicion of a government with access to many systems (telephone systems, etc.) is hard. Which is probably a good thing. Terrorism is a problem of technology. 300 years ago it was nearly impossible for a few guys to kill thousands -- they'd be apprehended and stopped first. Today, there is more and more technology that empowers individuals to kill may people. This goes back to the machine-gun debate, but basically as capabilities grow (3d printers printing guns, for instance) so does the surveillance. Sadly the surveillance isn't going away, because the technology for both is only increasing.

joe_the_user 13y ago

The methods supposedly used by the CIA here seem terrible for the reasons mentioned (especially always meeting at the same pizza place). My knowledge of intelligence comes mostly from old movies but it still feels like I could have thought of something better. My guess is the methods were really simple just to keep people from screwing it up, that the thing about complicated methods is that they fall apart from people forgetting all the complicated schemes and so they're worse than simple methods (sometimes). But that's just a guess, anyone know?

ballard 13y ago

Suppose to ensure anonymity, let's call a hypothetical anonymous, encrypted mixnet overlay service : Cone of Silence. CoS has two types of N nodes: relays R and clients C (Csrc wants to send packets to Cdst). Every nodes, N, talks to each other at constant rate B. Directional asymmetric rates are allowed. If there is nothing to send, a packet containing the output of a CSPRNG must be sent to meet B, which will be dropped by the other node. Every link in each direction maintains B. C must use at least 1 node to talk to each other. Direct C-C traffic and network loops are expressly forbidden. C must agree to encrypt the contents of their opaque application payload, P, amongst themselves. R informs Csrc of the list keys (k0, k1, .. kn) to recursively encrypt P with, resulting in payload to send, M = E(kn,..E(k1,E(k0,P))). Keys must never be reused except given the same Csrc to Cdest, but only for a maximum time and number of bytes. M is decrypted by each node and forwarded on to the neighbor if it is a valid packet. N must never know the complete path a beyond the neighbor node with which to send a packet and the specified path nodes. N must be assumed to be hostile. -- The reason for russian dolls encryption per link is to prevent correlation analysis. Lots of unanswered Q's: - Node discovery / reachability - Node impersonation (remember tcp connection hijacking?) - Hostile nodes (relays and clients), especially hostile relays that prefer to connect to each other. Perhaps clients (Csrc and Cdest) each specify a small # of nodes that a path must traverse. Periodically check with each specified node with a challenge to verify path integrity? (There must be a better way to ensure path integrity using crypto without backchannels to specified nodes.) - (D|)DoS - limits for all operations. Exponential backoff. - Crypto specifics, key scheduling, rotation, minimum&maximum rekey rate. - Packet particulars (packet size tradeoff: overhead vs. latency), transport/s (TCP sounds easiest), reconnection. - Multipath? Just say no (at least initially). - How is this better than tor? (Statistical analysis may prove if a host belongs to CoS, but not to whom. Tor may not be sufficiently mixed under "capture everything".) - Node identifier? 384-bits is plenty.

kbart 13y ago

I see the only lesson here: NEVER use cell phones for activities that you want to keep secret. They are known to be easily trackable and heavily backdored. Linux netbook (single-use&destroy for extra credits) with TOR + encrypted mail or IM on public WiFi networks would be much more secure and not so impractical on such high stakes.