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HTTPS Interception Weakens TLS Security

us-cert.gov

91–100 of 105 posts

Re: HTTPS Interception Weakens TLS Security

#91

Earlier quoted context omitted.

This is exactly what my company went through just a few months ago when we hired an IT security guy whose first order of business was setting up a Palo Alto Networks firewall. Before turning on the MITM functionality he gave a presentation to everyone about what it did, and nobody (support staff, developers, administrators, management...nobody) seemed to mind except for me. This was what I sent to the HR lead immedia…

But it's far worse than that. Look further down in the thread where a security guy has pre-emptively invoked the "acceptable use" policy to cover for up for incompetence to secure the MITM proxy appropriately. Acceptable use policies are not self-enforcing, they are really only used selectively, regardless if they say you shouldn't use your computer for personal use. Everybody does that to some degree and it is accep…

I very much agree with all of these points, which is why, as I told my HR rep, I won't use any personal websites on the work network at all since the HTTPS interception was turned on. It's been a gigantic pain in the ass doing things like checking my bank statements or whatever on my phone only, but I live with it. The only non strictly work related site I go to is this one, with this throwaway account/random password.

On the topic of liability and owning up to a potential hack, I think my company would be transparent about it, based on a history of being transparent about many atypical things in the past. We're not public, never received any VC funding, and nobody has any equity stake in the company except for the owner, who himself goes over the entire company's income statement in front of all the employees once per year to let us know where all the money's coming from/going to. I do believe he would do whatever he could to make it right, because the buck stops with him and him alone.

Clearly that's only a small comfort if our personal information is leaked, but I don't think in my case it would be covered up. I could certainly see that being the case in most corporate structures, though.

Re: HTTPS Interception Weakens TLS Security

#92

any recommendations on tutorials/guides for better understanding the world of TLS, certificates, and so on? i don't feel like i have a healthy mastery of the ideas discussed in articles like this one.

Ivan Ristic's "Bulletproof SSL and TLS"[0]

[0] https://www.feistyduck.com/books/bulletproof-ssl-and-tls/rev...

Re: HTTPS Interception Weakens TLS Security

#93
post #9

It might weaken TLS, but it also stops the 3000 head of cattle I managed from being able to watch porn (6 incidents) and torrent movies (47 copyright notices). If their internet banking, which they're not supposed to be doing at work, gets compromised then I really couldn't care less.

1. Snooping on their internet banking is ILLEGAL for you to do and puts YOU in hot water. You realize you could be put out of business by lawsuits right?

Re: HTTPS Interception Weakens TLS Security

#94
post #35
post #31

Earlier quoted context omitted.

If an organisation has a large number of networked computers on Windows XP they are going to have more issues than that - having no SNI support is one.

If you have an SSL intercepting proxy then you don't need SNI support on the clients.

If this is an explicit proxy, this is true. But with a transparent proxy, SNI would still be needed to know what domain name is going to be requested.

Re: HTTPS Interception Weakens TLS Security

#95
post #45
post #13

Earlier quoted context omitted.

There is limited distinction there. Both terminate and re-establish TLS sessions.

I strongly disagree: who is in control, how it is implemented, and the purpose of the product are all both extremely important and fundamentally different between the two use cases. An "antivirus" filter ends up implemented as a man-in-the-middle attack between software I wrote and servers I contract and control, wherein protections that were actively put in place are stripped away in order to increase the attack sur…

You seem to think whoever opts into adding it to the pipeline makes the difference (client vs server). It doesn't. Consider that a client in a remove location can build in a caching load balancer into their pipeline that you wouldn't realize is present that is built with exactly the same software you would put into your pipeline.

Both clients and servers can have TLS terminating things in the chains that perform arbitrary functions. All of them increase attack surfaces and risks of implementation bugs.

Re: HTTPS Interception Weakens TLS Security

#96
post #69
post #25

Earlier quoted context omitted.

Because if you block it then they can't do it and you have nothing to report. Everyone wins.

That's one way to see it. In my experience, those proxies in schools are a great way to motivate students to self-educate about how the internet works and about online privacy tools like TOR...

Why is a proxy necessary for a student to self-educate? Are you just saying this is a lesson they learn the hard way once they have been spied on?

Re: HTTPS Interception Weakens TLS Security

#97

Earlier quoted context omitted.

No, they haven't. They say pretty plainly that you need to ensure that such products provide correct certificate validation, since the client cannot do so reliably.

>> The US government has basically declared "HTTPS/TLS Interception Considered Harmful". > No, they haven't. The original report headline from US-CERT: "HTTPS Interception Weakens TLS Security" That seems pretty unambiguous, regardless of your personal feelings regarding CERT or whether it speaks for the broader US government.

Don't analyze a book by its cover!

Re: HTTPS Interception Weakens TLS Security

#98
post #94
post #35

Earlier quoted context omitted.

If you have an SSL intercepting proxy then you don't need SNI support on the clients.

If this is an explicit proxy, this is true. But with a transparent proxy, SNI would still be needed to know what domain name is going to be requested.

With HTTPS, the Host: header, which is precisely what SNI was designed as a use-case for, can be used.

Re: HTTPS Interception Weakens TLS Security

#99
post #24

So how do I test if my workplace is doing a good job of this? The article mentions badssl.com. Do I just click all the red links in the certificate section and verify that my browser is refusing to display the pages?

Click the Dashboard link at the top-left.

https://badssl.com/dashboard/

Re: HTTPS Interception Weakens TLS Security

#100
post #94

Earlier quoted context omitted.

If this is an explicit proxy, this is true. But with a transparent proxy, SNI would still be needed to know what domain name is going to be requested.

With HTTPS, the Host: header, which is precisely what SNI was designed as a use-case for, can be used.

But you see the Host header after the TLS handshake, after the certificate was sent. The poitn of SNI is to indicate the host header during the TLS handshake so that you get the right certificate. HTTP with the host header is one layer up. Again, this is for transparent proxy where no CONNECT is being sent.
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