DEF CON 31 - certmitm Automatic Exploitation of TLS Certificate Validation Vulns - Aapo Oksman

TLS is the de facto way of securing network connections. It provides an easy way of ensuring confidentiality, integrity and authentication for any type of communication. However, like most things in life, this is also too good to be true.

TLS allows communicating parties to uniquely authenticate each other by validating each other's certificate. However, many TLS libraries and frameworks have insecure default settings or allow for the developers to skip important aspects of certificate validation in their client implementations.

This talk explores issues in TLS client certificate validation and the underlying reasons why developers still fail to implement TLS correctly. Most importantly, we hack all the things with a new TLS mitm tool: certmitm.

certmitm automatically discovers and exploits insecure certificate validation vulnerabilities in TLS clients. Let's use the tool to hack iOS, Windows 11 and more while we deep dive into the world of insecure TLS certificate validation.

[stubstunner]

Excellent presentation.

I’m not sure that people entirely understand the scope of this right now. It took 14 years, and it still got to this point.

[spacenomad]

Sorry to my co-worker who once a year asks why don't just issue more certificates from the one we already bought.
You were right, we could've just issued some more.

[DedmenMiller]

I implemented cert validation years ago, but for executable signing. I knew i was probably doing it improperly as i had no idea what i was doing. This tool will be awesome just for the test certs generation

[xXBlackAngelDoomXx]

Very interesting talk. I think we can at least be safe that safe DNS protocols like DoT or DoH and encryption via WPA2 partially guarantee some safety via these not secure TLS connections, but of course this is not sufficient to conclude that TLS is useless and should behave this way! Corporations that replied to you defending themselves behind the assumptions of safe connections/connections made to "private connections" (in contrast to public unsafe ones) are using some coping mechanisms to not accept their responsibilities!

[JonJaded]

Excellent! Great talk and very informative.

[PexiTheBuilder]

As Fin can hear pain of being in spotlight. Can only imagine how wasted been after this.. :D

[hackjealousy]

So bad it had to have been done on purpose.

[KieranFoot]

Out of scope. Because secure transfer of data over a public network isn't a requirement for a secure system/application :P