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An analysis of the Nomx secure communications device

scotthelme.co.uk

21–30 of 77 posts

Re: An analysis of the Nomx secure communications device

#21
I STRONGLY recommend reading just the first bullet point below.

I'm wondering whether this is someone running a scam or whether they don't fully understand technology and some evil tech has taken them for a ride. It's that bad.

Some paraphrased/elided highlights from the article:

--

Practicality as a secure mail device:

- The TL;DR of the "unbreakable security" is that the device sends TLS-encrypted email on another nomx device listening on port 26... USING THE DEFAULT "snakeoil" Postfix TLS CERTIFICATES.

- The device sends from port 25. Or rather, it tries to - it worked for the post author, but I can personally say this would not work for me; my ISP blocks port everything outgoing on port 25.

- The device tries to relay mail from a residential IP. Predictably, all commercial email systems shut this down the moment they see it. Hotmail has the decency to actually kick the email back; other providers seem to just silently drop it.

- The device will immediately put your IP on DNS blacklists because you are sending mail that looks 100% like spam. These blacklists are used by a variety of online services so this is likely to catch up with you in a big way eventually (one thing I just wondered is whether Google checks your IP this way when deciding how complicated to make the captchas it sends you).

- When you set up a link to another nomx device (it calls this a "handshake"), you have to do it by IP address. There is no mechanism to autoupdate the remote IP (I do acknowledge such a system would be mildly nontrivial to put together, but I think this is already at the "doing it wrong" stage and this type of solution is not what is needed here).

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Security considerations:

- The default credentials are "admin@example.com" + "password" and there is no requirement to change this upon login.

- The device is so full of vulnerabilities it's possible to pwn it by simply visiting an arbitrary malicious Web page (from any web site on the Internet) that scans your network to find the device - once that's done the malicious page can fire off a series of form submissions (probably also doable via XHR) to gain a login cookie, create a new admin user that will not be visible because the device is only capable of listing one admin, and then...

- With the device pwned, it's possible to take it over completely, create arbitrary incoming email addresses, and attempt to send mail from the device, from your IP. Your computer doesn't even need to be on for this to work, obviously. I say attempt to send mail because most of it will be blocked, but you could easily take someone down by sending highly offensive mail to a provider that let the email through - bam, your IP is on file as having sent the email.

- Thunderbird required repeated manual verification of the device's TLS certificate (something the device purports not to require!).

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Software versions:

- Raspbian GNU/Linux 7 (wheezy) - last updated 7th May 2015

- nginx version: nginx/1.2.1 - released 5th June 2012

- PHP 5.4.45-0+deb7u5 - released 3rd September 2015

- OpenSSL 1.0.1t - released 3rd May 2016

- Dovecot 2.1.7 - released 29th May 2012

- Postfix 2.9.6 - released 4th February 2013

- MySQL Ver 14.14 Distrib 5.5.52 - released 6th September 2016

The author received no response to his requests for updated versions of the software.

The device also has no autoupdate mechanism, and there is also no mention of such a mechanism being in development.

--

Other thoughts:

- The device uses GoDaddy for dynamic DNS. I'm curious why this is so bad; is it because GoDaddy DNS doesn't update rapidly?

- This kind of reminds me of http://thedailywtf.com/articles/The-Expert-System

Re: An analysis of the Nomx secure communications device

#22
If i understand this correctly, the device is (apart from being the least secure thing ever) basically useless at it's function, since it doesn't support SPF/DKIM/DMARC and you can't get it to use HTTPS and as such will bounce off every single correctly configured email server in the world?

If i remember correctly, when i tried to setup my own email server with my domain on a VPS box, i had to go through the whole nine yards of getting a letsencrypt cert and setting up lots of voodoo stuff before i could send mails to anyone but myself.

Also, how are you supposed to use this at home at all, if most residential ISPs (at least here in germany) block any Port 25 traffic?

Re: An analysis of the Nomx secure communications device

#24
While I have a summary post elsewhere in here, at the risk of being a bit spammy I'm double-commenting the following bit:

The device is designed to send TLS-encrypted mail from nomx device to nomx device on port 26, BUT IT IS ENCRYPTING USING THE DEFAULT Postfix "snakeoil" TLS CERTIFICATE.

Re: An analysis of the Nomx secure communications device

#25
post #11

Earlier quoted context omitted.

Its port 26 enforces TLS though.

But doesn't bother to check if the certs (local and remote server) have been signed by a trusted authority. Nor does it attempt to pin these certs. It provides encryption, but no authentication nor authorisation. In short an ever so slight improvement over normal SMTP.

It's actively ten thousand times worse than that. From the article:

> The device uses self-signed certs throughout and they aren't even device specific. It's using the default ssl-cert-snakeoil.pem and ssl-cert-snakeoil.key in the Postfix config.

Re: An analysis of the Nomx secure communications device

#27
post #22

If i understand this correctly, the device is (apart from being the least secure thing ever) basically useless at it's function, since it doesn't support SPF/DKIM/DMARC and you can't get it to use HTTPS and as such will bounce off every single correctly configured email server in the world? If i remember correctly, when i tried to setup my own email server with my domain on a VPS box, i had to go through the whole ni…

Yes to everything you said.

D:

Australian ISPs kill anything outbound on port 25 also.

Re: An analysis of the Nomx secure communications device

#28

I really can't tell whether this is an outright scam, or an earnest attempt by someone completely unqualified (and completely unaware that they're unqualified, per Dunning and Kruger).

I actually wondered the same thing in the summary comment I posted.

Re: An analysis of the Nomx secure communications device

#29
post #13

Can't wait for their $10k bounty program to go public. That will be an easy win for whoever submits first.

The article mentions that the bounty private key(s) would be embedded within the device, so I don't think a submission would be necessary.

Now that's just double stupid. Just dump the flash and done.

Re: An analysis of the Nomx secure communications device

#30
post #19

I find these kinds of stories infuriating (and just a bit frustrating). Charlatans repackage, rebrand, and repurpose FOSS, then sell them at an unrealistic markup to unsuspecting dupes. Anything from PABX or VoIP systems based on Asterisk, through overly complex CMS's based on Wordpress. I'm not sure what riles me more: consumers being ripped off by these products, or the fact that my strengths lie in tech rather tha…

If you are distributing a product using GPL code aren't you supposed to explicitly display the license in the product manual or somewhere else ? The end user is not supposed to have to open a product case to find out... I have not seen it mentioned in the original post. So this is a license infringement as well.
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