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Gogo forges YouTube SSL certificate to throttle high-bandwith usage on flights

It swears it's not intercepting user data, but issuing a fake HTTPS certificate sure doesn't make us feel warm and fuzzy.

Plane. Image courtesy of Shutterstock.If you like to keep connected while you’re up in the air, you should be aware that the in-flight Wi-Fi service Gogo is pulling what some are characterizing as a man-in-the-middle attack by issuing fake digital certificates as a way to throttle high-bandwidth websites.

Google Chrome security team engineer Adrienne Porter Felt first noticed the bogus SSL certificate while trying to get to the (Google-owned) YouTube site during a flight.

Instead of receiving the Google-issued certificate she expected, she got one from Gogo, with a red-letter warning saying that it came from an untrusted issuer.

She tweeted the certificate late last week and asked just what, exactly, was Gogo up to?

APF tweet

hey @Gogo, why are you issuing *.google.com certificates on your planes?

It’s understandable why she’d be concerned and why privacy and security experts are reaching for the aspirin.

While modern-day browsers, including Chrome, will flag a bogus certificate, the practice of issuing fake certificates could, at least in theory, set Gogo up to be in the same position as the man in the middle of a man-in-the-middle (MitM) attack, issuing fake security certificates that allow it to view passwords and other sensitive information exchanged between users and YouTube – or whatever other service Gogo might use the technique to block.

The way it’s supposed to work is that the SSL/TLS protocol ensures a route for secure communication with the use of SSL certificates, making it difficult for sensitive data such as credit card numbers or passwords to be intercepted.

In order to succeed, a MitM attack requires an attacker to set up a mutual authentication between two communicating parties.

Cryptographic protocols provide some form of endpoint authentication – Secure Sockets Layer (SSL) is typically used to authenticate one or both parties, with a mutually trusted certificate authority – specifically to block MitM attacks on users.

Snooping on someone’s communications would require an attack on that SSL certificate.

Learn more

In response to Felt’s text, Gogo Executive Vice President and Chief Technology Officer Anand Chari released a statement saying that the broadband provider is absolutely not stealing users’ private data.

Rather, the rigged certificate is all about enforcing the company’s no-streaming policy, he said.

Gogo uses several techniques to block or limit video streaming, he said, including a recent off-the-shelf tool that proxies secure video traffic in order for Gogo to block it.

In fact, Chari said, the use of the technique to “shape bandwidth” only affects some secure video streaming sites and doesn’t affect “general secure internet traffic”.

It’s meant to ensure that all those who want to use Gogo get a fair shake at a decent browsing experience, and not as a way to grab users’ private information, he said:

We can assure customers that no user information is being collected when any of these techniques are being used.  They are simply ways of making sure all passengers who want to access the internet in flight have a good experience.

Felt says that she wasn’t actually trying to stream video when she received the false certificate and was instead only trying to fix a broken YouTube page:

APF tweet 2

@iamchrisle oddly enough I wasn't, I noticed this when debugging a page that seemed broken (it had youtube in an iframe)

The security engineer herself doesn’t believe that Gogo is up to anything maliciously MitM-ish, though she did tell the Google account manager to kill active sessions:

APF tweet 3

@anlumo1 @parityzero nah, I don't think they're doing that. (but I did tell the goog account manager to kill all active sessions.)

If a Google security engineer isn’t worried about this, perhaps we can all unhunch our shoulders a bit?

Or perhaps not.

After all, Gogo was recently caught bragging about how it goes above and beyond to enable the US to snoop on passengers.

Perhaps we should still keep a watchful eye out – not just on Gogo, but on any company that feels justified in falsifying SSL certificates a la malicious attackers.

Image of plane courtesy of Shutterstock.

0 Comments

Am I mistaken, or isn’t man-in-the-middle a standard procedure for web filtering? I think pretty much all of the web filtering appliances do it.

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Correct. Click on the yellow “Learn more” in the article to, errrr, learn more about how that works (and how it can go wrong).

Actually, here’s that link again:

https://nakedsecurity.sophos.com/2013/12/09/serious-security-google-finds-fake-but-trusted-ssl-certificates-for-its-domains-made-in-france/

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A cautious person would also notice that there plenty of loopholes left by the wording used in Gogo’s response….

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If they want to limit bandwidth hogs, they should do that directly. If a device is using more than its fair share of bandwidth, throttle it or cut it off. They don’t have to issue forged certificates or keep track of which sites are “good” or “bad” to do that.

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I agree. There are plenty of ways to throttle individual devices or individual connections without needing to inspect the traffic payload. From a network design and cost perspective, I’d prefer to stay out of the application layer for this task.

Their actions and their stated motives don’t line up 1:1.

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If you want to allow some sort of limited or managed access to YouTube, then taking a look at what the user is going for _does_ make sense. You can argue it’s not miles away from the need to peek inside TLS if you want to do selective content and malware filtering on email and web traffic.

As long as you are clear enough about what you’re offering when you put your users through your captive portal when they sign up in the first place, is this really a big deal?

(And, having mentioned captive portals…isn’t a Wi-Fi “pay page” pretty much the same thing from a “what are you looking at” perspective? That’s where you create a bogus DNS and redirect *all* the users’ traffic to a placeholder page until they have signed up or logged in. The problem with a portal page or proxy of any sort over TLS is that you have you present a certificate first, which produces a warning up front.)

You can do exactly this sort of HTTPS content inspection in Sophos’s UTM and Web Appliance products (the former is 100% free for home use, see right sidebar :-), so it’s not exactly unusual, nor is it particularly high-cost. OTOH, I suspect that “from a network design and cost perspective,” as you put it, the air-to-ground linkup for in-flight Wi-Fi is the tricky/costly part, easily exhausted by video-hungry passengers and well-worth managing more closely than on a terrestrial network :-)

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i was going to mention the Wi-Fi access scheme (encountered it most recently last night) but you beat me to it.

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Seems to me that this is not good news for unsophisticated/average users. They don’t know what to choose when they get an certificate error as it is. This trains them to just go “oh, well that’s OK.” Then, the next time they’re at a coffee shop and someone is actually trying a MitM attack, they might just go, “oh, well that’s OK” to any certificate warning the browser throws up.

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Why one could be sure none will try this type of attack in the plane? The sertificate is forged anyway so none will become suspicious about forgery.

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Good point. Especially if the little laminated “how to use Wi-Fi n flight” card in the seat pocket includes a warning that accepting the access point’s proxy certificate will be necessary…

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All passengers would have to do is connect to a vpn then visit the streaming site.

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Or you could just take a book with you. Instant on, high-resolution text, the batteries never run out, they keep running even if someone spills red wine on them, and they even work offline.

Oh, and no DRM, so you can swap with another passenger when you finish.

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There are much better ways of traffic shaping than this.

In my opinion, an SSL certificate is like a signature (actually, it IS a signature).

Forging someone else’s signature is a serious crime and forging SSL certificates should also be a criminal violation with serious penalties.

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You all realize that Gogo is providing internet access on an airplane?
Gogo can not handle HTTPS connections at all.

The airplane flies from Miami to Dallas.
The passenger wants to access HTTPS Gmail.
As the plane flies, it connects and disconnects from several Internet Service Providers.
Gogo can not provide a stable HTTPS connection.
Gogo has to fake the HTTPS connection.

And of course, streaming video will never work when flying across the country. How could streaming video ever work in this setup?

As the internet becomes more secure, and HTTPS websites more common, the Gogo service becomes less workable.

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