more realistic interpretation: Intentional backdoor for NSA programs as skype has already been shown to be a part of.

http://arstechnica.com/tech-policy/2014/12/newly-published-n...

If Skype wanted to give user data to the NSA, they would send it over from their servers instead of implementing a backdoor that requires the NSA to already already have software on the target's computer (at which point, assuming they managed to get root, they could circumvent whatever protections Skype was using anyway).

Big corporations are, by definition, large complex organizations. There is legal, executive management, developers, ops, etc. Hypothesizing about their actions as a singular entity can over simplify things. I don't know about the specifics in the article, but as a general rule there are a number instances where an intelligence agency may approach only a developer, an ops person, or someone in legal to obtain what they want instead of showing up and serving the corporate entity with a NSL. Saying the organization as a whole could provide data exfiltration much more efficiently by other means, does not rule out the possibility that other techniques could be used instead for various non-technical reasons.

You didn't respond to the substance of his objection. The problem with the "NSA backdoor" hypothesis is that it doesn't make logistical sense: it requires the NSA to already have installed software on the victim's computer. If the NSA has installed software on your machine that it can control, you are going to, in the parlance of our times, "get Mossad'd".

Of course, of course, this is unlikely to be an NSA backdoor. But maybe .... </CK_LOUIS>

i dabbled in this api way back in the past so i may be wrong about its capabilities.

skype used to be EXCELLENT at working in most networks, including "locked down" corporate ones. Network admins used to find it notoriously difficult to "ban" on networks.

so relying on skype to exfiltrate info may serve two purposes:

1) use another program's capabilities instead of reinventing the wheel.

2) hide the fact that some random program is doing network access.

skype could be one of a range of data exfiltration mechanisms with different levels of obfuscation.

> it doesn't make logistical sense: it requires the NSA to already have installed software on the victim's computer.

Well, if you have any of the closed-source companies' software on your system (and by definition, that is +/- 310mio citizens, in the US alone), you are sure to have NSA backdoors on your system. Such backdoors certainly do not require manual intervention for them to be exploited on large scale.

Explain?

No one outside of the software provider can audited the code, and presumably even they haven't audited the code. Recently there was the source code backdoor that was suspected to had been placed inside Juniper routers by the NSA. If I remember correctly, it wasn't found because it was hidden on a high right column.

The Juniper backdoor was a bit particular in that it was known that the code in question had been developed and distributed by the NSA. It's more of a stretch to accuse every single vendor of proprietary code in the USA of building NSA back doors into their products. It would require the knowing assistance of tens of thousands of people across those companies.

My point was that you don't actually know, and you don't technically need all the vendors. Just the big ones, and there's not really that many. Even more to the point, you don't even need all of the big ones, just the ones on the biggest network, which honestly probably just one vendor on the whole network due to volume purchase discounts and interoperability concerns.

But more to the point, you don't know what's going on in closed source code. It's trust. However the trust can, and has been violated in the past (whether by the provider or by a third party is immaterial). You just don't know. Now that doesn't mean that open source software is immune. I seem to remember there was a backdoor found in the Linux kernel a few years ago. These things happen, but at least it's easier to audit.

Can you give an example of one of these instances? I've heard of this sort of thing outside of the U.S. (James Bond bribes East German clerk to get the microfilm), but I haven't heard of domestic agencies doing this in the U.S.

Isn't it already disclosed in the Snowden documents that Skype has received NSLs?

Here is a recent article discussing the DEA doing this: https://www.washingtonpost.com/news/powerpost/wp/2016/09/30/...

$600k to a particular airline employee, $1 million for a single parcel worker (this was over a few years).

Also there is the various NSA efforts to insert people into the encryption standards process, as well as use cooperative sources within companies to insert vulnerabilities in the commercial encryption systems:

http://www.nytimes.com/interactive/2013/09/05/us/documents-r...

Also the FBI/Yahoo email program was apparently done by just the CEO, a lawyer, and a few members of the email team. The security team wasn't informed, nor the board.

https://www.theguardian.com/technology/2016/oct/04/yahoo-sec...

The DEA program is pretty shocking and a great example, thanks for sharing!

The second one sounds more like an interdiction program, where vulnerabilities are inserted into the devices (this is a thing that was in the Snowden documents). The document gives no details. The highlights on the side are from an NYT journalist, not source material.

I disagree that the last example is an example of that. It's still unclear what the scanning was doing.

The Yahoo thing is a huge deal. Email providers do interception all of the time and have strong procedural controls.

The idea that people could bypass those processes and controls is a tremendous liability that no board would ever approve.

First of all, Skype is Microsoft. Second, they're well known to collaborate already. If NSA wanted a Skype feed, they could have it server or client side.

https://www.theguardian.com/world/2013/jul/11/microsoft-nsa-...

Originally, and perhaps at the time this "backdoor" was created, Skype wasn't Microsoft.

Skype was around for along time before Microsoft bought it and changed its architecture and design.

This. It could well have been a backdoor that predates the "superpeer" change MS introduced right after acquisition. Skype was already under pressure from European authorities at the time, to provide intercept capabilities; European criminal networks (mafia etc) were early adopters and everybody knew it.

That collaboration looks like the same mechanism used to adhere to warrants, subpoenas, and NSLs. Do you think that any internet service in the world doesn't have similar mechanisms to comply with law enforcement requests in their home country?

I think you are misleadingly using the word "collaboration".

I also think you have failed to understand the article correctly; there is no reference to client side collection. Take another look.

Agreed. I'm just suggesting if someone were to ask for a client backdoor they could have one, just like they could ask for a server feed.

NKW gave a nice summary of some recent actions. For more historical examples, I highly suggest any of James Bamford's excellent books on the NSA. _The Puzzle Palace_ is a massive tomb, but a very good read. I haven't had a chance to read _Shadow Factory_ yet, but it is in my pile.

How do you think that Juniper VPN compromise got inserted into the code?

In the "Athens" affair, most commentators dismissed CIA involvement saying that if the US gov needed the data, they could just ask.

Well after the investigation went through and some data came out regarding the Vodafone server hack it was clear that the organizations that could pull something like this, there like ... Maybe 5 with CIA the most likely candidate.

So, we like to oversimplify but life is way more complicated.

BTW I think that the Athens affair is one of the top 3 hacking stories that I know of.

Skype used to be a peer-to-peer application and did not use nor require any "central" servers.

Then, Microsoft bought it and that all changed.

Disclaimer: ex Skype employee here

While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and conclusion (MS made it a client-server system because Evil).

- Real peer to peer on internet is not really possible, since most end users are behind NAT. Skype resorts to a number of hole punching techniques, but really only uses STUN/ICE, effectively using super-nodes as relay for sessions. This directly means that all these communication are transiting through a third party, and not peer to peer.

- Super-nodes used to be regular end users (with some simple algorithm to elect as supernode users with high up-time, high throughput. Fun fact: only windows client users were possible super-nodes). This model proved to be too fragile. In case the network falls down (which happened some years ago), then the super-nodes are no longer available, and get instantly DoS when coming back up due to every other node trying to get back. This is a vicious cycle in which the network cannot get back up. So for a long time now (before MS) super-nodes are just backed by Skype-hosted servers in data-centers.

- Thin clients are a real thing in e.g. the african market, where a lot of very old phones are still in circulation, no "apps" are possible. Think of your old Nokia 3310.

- Persistent group chats. Users wanted it.

- And on a more "political" aspect: MS needed to promote its cloud infrastructure (Azure), lower its physical resources fingerprint (get rid of Skype datacenters), and unify its technical stack (Linux/C++ now Windows/C#)

Skype claimed that the move to central servers was because peer-to-peer would not work on smartphones which were becoming their user base.

The old Skype for Windows was really locked and obfuscated. I remember that it would not even start on my PC with a debugger installed, even though it was not running in the debugger.

You forget that Skype used to be peer-to-peer.

You mean more paranoid interpretation.

Microsoft controls the servers, they don't need a client backdoor to access messages.

>You mean more paranoid interpretation.

honestly it amazes me that people still call such interpretations paranoid in a world where information about the rampancy of such programs is readily available, including for this specific application

Edit: it's not paranoia if there's demonstrable history of such things. It's making a reasonable assumption from available facts.

further, all the arguments against this interpretation assume that those introducing security vulnerabilities for surveillance purposes abide by some kind of logic - which by the very nature of such activities they demonstrate that they do not. They (3 letter agencies) want every possible vector of information gathering regardless of the privacy, security, and legal issues that arise.

It seems to me to be a paranoid interpretation because if Microsoft wants to hand Skype-related user data over to the NSA, they'll do so on the server side and not the client side.

Secondly, this is a pretty stupid way of doing it. 'If you use this client identifier than anything goes' seems vastly more like a stupid coding mistake than it does a sneaky covert backdoor into accessing Skype from the local machine.

If I wanted to hand user data over to a 3rd party that tapped the entire backbone, I'd make that user data unencryptable. Why would I want to send Gbps of traffic to that third party? Then everyone would know. If they can just analyze the recorded traffic, none has to know.

Intelligence agencies want as many possible vectors for attack as possible. Especially unknown ones that you are not prepared for them to exploit. Everyone is assuming they wouldn't bother with a client backdoor... That right there is enough reason for them to get a client backdoor!

>further, all the arguments against this interpretation assume that those introducing security vulnerabilities for surveillance purposes abide by some kind of logic

Of course they do. You may disagree with the logic, but it's there. Vectors of intelligence gathering have to be both sufficiently covert and useful for an agency to consider. This vulnerability is neither.

So far you haven't said anything more than "NSA exists, therefore all software insecurities are reasonably attributable to them".

sure! Oh except for the fact that i linked an articule documenting skype specifically catering to NSA surveillance programs, and the NSA having a history of getting software to introduce vulnerabilities they can exploit...

but hey, why not throw out the facts to pile on?

It's the facts that are the problem with your weird theory: this doesn't even make sense as an NSA backdoor. It only works if they've already backdoored your computer.

Does any NSA surveillance vulnerability stand up to logical scrutiny?

No, because introducing security vulnerabilities to keep us secure is inherently illogical.

If this comment made sense to someone else who could rephrase it for me, I'd be grateful.

I think he means 'if nsa were logical actors, they would patch vulnerabilities, not leave them to be exploited by anyone, and they would use NSLs/collaborators/special NSA Voodoo to get their data'.

This idea is built on the assumption that (1) they think their defensive role is as vital as their offensive one, (2) there is plenty of special NSA voodoo to go round. Which is false. In particular, it is better that a hack come from a vendor vuln that anybody could find than from crypto wizardry (e.g. Logjam or signed drivers with md5 collisions).

The NSA did an illogical thing, therefore everything they do is illogical. It is illogical to create a backdoor that requires already owning the machine, therefore the NSA did exactly that.

This is also the biggest fallacy in economic, and even political theory. The assumption of rational actors.

If you have reading comprehension problems, sure, that's what he said.

Just because it has happened doesn't mean it's always happening. Without any proof of intent, yeah, I'd consider it (plausible?) paranoia.

Exactly right. Skype used to do peer-to-peer connections with nobody in the middle. If you knew how to modify the port forwarding configuration of your router, you could get very high quality connections.

Now, everything goes through Microsoft servers where it can be conveniently wiretapped.

Skype used to do that ... with an obfuscated proprietary software blob. There's no reason to think they didn't have the ability to reroute on demand.

But if they wanted plausible deniability when they get caught...

Or, the inherent backdoor in poorly encrypted VOIP without proper packet padding: http://cs.unc.edu/~fabian/papers/tissec2010.pdf

EDIT: Also: http://www.cs.unc.edu/~fabian/papers/foniks-oak11.pdf

That is not at all a realistic interpretation. This is an 'authentication bypass' for a Skype API for locally executed code. Any even slightly serious attacker who has got to that point has already won - they don't need a 'Skype backdoor'.

Are Mac OS apps unable to debug other applications or generally mess with their process space? If so, like on Windows, then this API is basically a courtesy and not a real security boundary in the first place.

I'm really just going by basic idea that once an attacker can run arbitrary code on your desktop, it's game over. That attacker doesn't gain anything by engineering and organizing some 'backdoor' into Skype, they've already owned you.

There is some basic sandboxing, for example a debugger cannot attach to a running copy of iTunes (but you can start it under gdb and bypass the call that enables the sandbox).

The problem with this interpretation is Snowden.

If Snowden didn't happen I would most likely believe that this was just bad engineering or something.

Post Snowden your interpretation sounds like extremely naive.

The backdoor allows access to the Skype application which is running in the same environment as the process 'abusing' it.

It's stupid programming and perhaps could be used for convenience by a worm or virus but it does not allow privilege escalation.

Worst case scenario there is a bug in the API that allows privilege escalation, then it might be a sandbox escape, if it is possible to use the API from inside the sandbox which I doubt.

Out of curiosity, why is the API so massive? I have not seen Skype's core features change over ~10 years. I know the architecture has been redesigned but the ability to make calls and send IMs surely goes through an underlying network shim.

Why the rest of it? Is it overengineered? Am I missing something?

most likely, too -- we can go on about state involvement etc, but without evidence I think ockham's razor applies here.

I think it's more in Hanlon's razor territory than Ockham's razor. It's absolutely not unheard-of to see deliberate backdoors in a lot of commercial software (usually as some debugging port that the devs didn't think anyone would find), but it's just much more likely that it's a product of incompetence than malice.