
NoSnoop – Find out if your HTTPS traffic is being monitored - svenfaw
https://www.trustprobe.com/fs1/nosnoop.html
======
fefe23
A tool like this should be running in a browser.

Otherwise, if the method of intercepting the traffic only manipulates the
browser (for example a rogue extension or proxy setting you were not aware
of), a standalone tool could not detect it. Right?

Also, I would generally avoid any security tools that do not come as source
code. Mentioning that you are an infosec guy with 15 years of experience only
makes this point hit even harder.

~~~
cheez
It's not possible to access certificates in the browser.

~~~
tialaramex
An extension can do it:

[https://addons.mozilla.org/en-GB/firefox/addon/certainly-
som...](https://addons.mozilla.org/en-GB/firefox/addon/certainly-something/)

------
Mizza
Does anybody remember a project called "Perspectives"? It was a Firefox plugin
that would verify your certificates and handshakes were the same as the ones
other users were getting. Cool idea.

~~~
c0nducktr
Yeah, it didn't really seem to take off but I had it installed for a while.

The site is still up. [https://perspectives-project.org](https://perspectives-
project.org)

~~~
kekebo
The addon appears to be missing though [https://addons.mozilla.org/en-
US/firefox/addon/perspectives/](https://addons.mozilla.org/en-
US/firefox/addon/perspectives/)

~~~
pabs3
The addon cannot work any longer because since the XUL to WebExtensions
transition Firefox no longer allows addons to make decisions about the
validity of https certificates. This killed off Perspectives and a number of
other addons implementing alternate trust models.

[https://bugzilla.mozilla.org/show_bug.cgi?id=1435951](https://bugzilla.mozilla.org/show_bug.cgi?id=1435951)
[https://bugzilla.mozilla.org/show_bug.cgi?id=1489080](https://bugzilla.mozilla.org/show_bug.cgi?id=1489080)

~~~
c0nducktr
I hope the functionality could be added back with an API.

Honestly I had forgot all about that addon until Mizza mentioned it, but I
remember being so impressed by the idea back when I first learned about it. I
wish we could bring it back.

~~~
pabs3
I'd suggest subscribing to the Mozilla bugs about this to get notified if that
ever happens.

------
akerro
There is also OONI for mobile from TorProject that does the same, app and data
are opensource. Available in FDroid

[https://ooni.torproject.org/](https://ooni.torproject.org/)

------
ianai
Anybody able to verify this does what it says? Random windows zip download
from a domain I’ve not heard of sounds pretty sketchy.

~~~
judge2020
> NoSnoop contains no adware, malware or sponsored content of any sort.

well it says this so no reason to distrust it :)

~~~
johnday
On the off-chance that this was said unironically, you should never trust
someone just because they say you should. _Especially_ if they aren't sharing
the code.

~~~
judge2020
It was sarcasm but you're right and a reader might not understand the joke.

~~~
mpfundstein
I think its pretty hard to not understand your joke.

------
BasicObject
Huawei is alerting for me.

www.huawei.com 0 Actalis Authentication Root CA
F373B387065A28848AF2F34ACE192BDDC78E9CAC

~~~
tialaramex
So what that means is that this software expected to see some other
certificate but instead it saw this one. huawei has had a considerable number
of wildcard (*.huawei.com) certificates issued for whatever reason
(configuration screw-up, somebody press the button too many times, different
teams with same job, this happens) and you can see a bunch of them here:

[https://crt.sh/?q=huawei.com](https://crt.sh/?q=huawei.com)

The software's assumption is that (for some sites at least) the author can
check what the "right" certificate is and if you see a different one that's
wrong.

That clearly won't work for some sites any of the time, they use a CDN to
present different behaviour including certificates in different places, and
presumably the author weeds those out. But as we see here it can't work for
_any_ site all the time, it will be inconsistent.

~~~
oefrha
> a considerable number of wildcard (*.huawei.com) certificates issued for
> whatever reason...

Is there any downside to this? I mean, I have several wildcard certs issued
for each of my personal domains mainly because it's more convenient to get
separate certs on each host with certbot than trying to sync certs from one
host to another. Is there any reason I shouldn't do this?

~~~
tialaramex
Yes, but the downside may be acceptable to you.

A bad guy who gets any of the private keys associated with any of these
certificates can use that to impersonate any service with the corresponding
name, even a quite different one.

So say you've got mail.oefrha.example that's a mail server using a
*.oefrha.example cert, and the Dread Pirate Roberts breaks into it, they can
use that when impersonating your web server www.oefrha.example or your Q&A
site faq.oefrha.example even if those are on totally different hardware that
Roberts wasn't able to penetrate.

For older TLS (or SSL) versions there's a trick called implied authentication
used with RSA. After showing the certificate, instead of your server signing
something to prove it knows the corresponding private key, the client sends
something across which your server decrypts. Only the real server could
decrypt it with the private key to continue the conversation so authentication
is implied. However, in doing this your server has to be _extremely careful_,
because it's easy to give away information when things go wrong. If it's not
careful enough, a bad guy doesn't learn the key but they can use your answers
to work out how you'd sign RSA messages.

This means if you've got old-crap.oefrha.example which does TLS 1.0 with
crappy RSA implied auth enabled so as to make it work with some rotten turn of
the century tech, and it has a wildcard certificate, some bad guys can maybe
exploit that to pretend they are www.oefrha.example even though your actual
www.oefrha.example web server only speaks TLS 1.2 or newer with elliptic
curves.

You say a "personal domain", and I don't recognise your name, so chances are
that this just doesn't matter. We're not talking about something a bored
teenager can do, but if real bad guys with resources are attacking you, then
it's probably not a smart idea to have so many wildcards.

Edited: Repeatedly to try to get HN's half-arsed parser to stop ruining
everything. Gave up. HN use a parser that has working escapes, or remove the
parser and just say the site only has text too bad.

------
utefan001
FYI, if you google mitm check you should see a link to this site. A service
provided by the caddy server devs. [https://mitm.watch/](https://mitm.watch/)

~~~
alibert
On my home network, I get the green OK page on my desktop computer on Brave
but I get the red `Likely MITM` on my iPhone with latest iOS.

How should I conclude?

~~~
sschueller
Via wifi or cell?

~~~
alibert
Same network for both: fixed ethernet on my desktop computer and wifi for the
phone.

I tried LTE only and I also get the red MITM page.

Edit: tried my laptop on wifi, green OK

~~~
cmg
Interesting. I tried on my home WiFi (Comcast) on my Mac - green page (no
MITM).

On my iPhone, (AT&T LTE) - red MITM page.

iPhone on my WiFi - red MITM page even with the cellular antenna disabled(!)

Tethered my laptop to my phone - red MITM page.

------
cascom
This is pretty low-tech but I think is pretty effective.

[https://www.grc.com/fingerprints.htm](https://www.grc.com/fingerprints.htm)

~~~
jf-
Would these be expected to change by country? I’m getting different results
from grc for Facebook, Wikipedia and others in the UK, but the results are
consistent between different connections. Results match for grc and paypal.

~~~
swalls
Also in the UK (ISP is Virgin), getting similar results: the extended
validation ones are the matching but the rest aren't.

------
wearedevo
This bit is interesting:

"This website does not collect any personal information." \- after taking
about the product for the entire page. Note "website", not "software".

------
tgsovlerkhgsel
There is also another project that uses not just certificates but full TLS
handshake fingerprints. The name escapes me, but it allows the _server_ to
determine whether it is talking to a browser, or the MitM proxy forwarding the
connection. (You could of course employ a similar technique on the client
side). Don't remember the name.

Both approaches have advantages and disadvantages (e.g. this one reports false
positives if the certificates change, the other either reports false positives
if the fingerprints change unexpectedly, or false negatives/inconclusive
results if it encounters an unknown fingerprint).

------
mikece
If it's a tool to verify that there's not an active MITM, how do you detect if
a MITM used a forged cert in lying that nobody is in the middle? In theory the
MITM would see both the outbound request and the response, putting them in
position to pull off a forgery like that.

~~~
oropolo
Q. Can I detect a MITM (machine in the middle) attack? A. No, not easily.

[https://security.stackexchange.com/questions/12066/can-i-
det...](https://security.stackexchange.com/questions/12066/can-i-detect-a-
mitm-attack)

~~~
acdha
That’s one answer of many and it’s wrong. A correct answer would discuss the
various active and passive detection methods and their weaknesses, and
especially how it’s easy to detect an unskilled attack but progressively
harder to foil a sophisticated one.

Simple examples:

1\. Analysis of TCP details could detect an intermediary proxy

2\. TLS conflicts tell you a bad attacker is trying; use of a certificate from
a different CA or an old one tells you someone has been compromised.

3\. Attempts to block or throttle TLS, downgrade protocols, or block/degrade
access to security updates tells you someone is trying to encourage you to act
in an insecure manner.

4\. If you send unique canary hostnames or URLs which are accessed, you know
something has compromised your traffic.

5\. Timing analysis can tell you that some target sites are being treated
differently, which could be a sign that traffic is being more tightly
monitored (IIRC this has been noticed with the great firewall).

6\. HTTP pages can be requested from multiple sources and compared for
modifications. I once learned about some JavaScript being injected into pages
on Iranian college computers when their code triggered errors this way.

------
CapacitorSet
I find it somewhat ironic that the tool is served over HTTPS over some random
domain. Certainly if an attacker has the resources to forge a certificate for
eg. telegram.org doing the same for trustprobe.com won't be much harder.

~~~
mosselman
I think the idea is that you already have this tool before you are mitm-ed.
Also, you don't really think that attackers are gods right? As in that they
know about every single website that could alert their victims of their
attack?

------
amingilani
Interesting. Is there a Mac/Linux version of a tool similar to this?

~~~
akerro
My other comment:

There is also OONI for mobile from TorProject that does the same, app and data
are opensource. Available in FDroid

[https://ooni.torproject.org/](https://ooni.torproject.org/)

~~~
gianpaj
100 MB for the Windows for Mac OONI Probe Desktop? Electron _face palm_

------
rand0mx1
Is this program any different from goodbyedpi
[https://github.com/ValdikSS/GoodbyeDPI](https://github.com/ValdikSS/GoodbyeDPI)

------
kuratkull
bbc.co.uk and huawei.com gave "ALERT"s for me. Manual verification shows the
cert chains to be sane. The application should give me more details about the
error conditions it hit.

EDIT: www.bbc.co.uk 0 GlobalSign 1F24C630CDA418EF2069FFAD4FDD5F463A1B69AA

www.huawei.com 0 Actalis Authentication Root CA
F373B387065A28848AF2F34ACE192BDDC78E9CAC

------
Krasnol
> Error initiating scan - Please check your internet connection.

Doesn't work here or should I be concerned? ;)

------
burundi_coffee
Is this FOSS?

~~~
kuratkull
I'm sure you could whip up something like this in about 10 lines of bash.

~~~
eurasiantiger
Is that a challenge?

