DEFCON 17: More Tricks For Defeating SSL
Why Information Security Stack Exchange recommends it
Security Stack Exchange answerers point people to it as the primary source for sslstrip, null-prefix certificate attacks and other ways HTTPS can be defeated in practice.
Recommended by 5 people across 5 different months, 2011 to 2020.
What it is
Moxie Marlinspike's DEF CON 17 talk, a follow-up to his sslstrip work, shows new ways to attack SSL/TLS where plain stripping does not reach, including protocols like IMAPS and SSL-based VPNs. It covers tools such as sslsniff and the null-prefix certificate trick for getting trusted certs for domains the attacker does not own. This upload is by a third-party channel, not DEF CON itself.
What people said
Strong rec chris · 2011-10 · Information Security Stack Exchange · on “How practical is a certificate's "basic constraint" property in protecting my HTTPS / SSL session?”
Moxie Marlinspike did a lot of SSL research. He presented some of it years ago, among which an overview of browsers ignoring the basic constraints. It seems to have been fixed now in most SSL implementations. However, [this video] is a very good watch if you want to know more about SSL vulnerabilities :-)
Recommends atorrrr · 2013-02 · Information Security Stack Exchange · on “Can URLs be sniffed when using SSL?”
When using HTTPS the traffic will be encrypted. The only catch here is that if a malicious user had access to sniff your traffic he may also be able to abuse act as the destination server and setup an encrypted connection with you that looks as if it is your bank. The attacker will then create another session with the bank and forward all your requests to the bank and all responses back to you. This gives you the illusion that you are in fact communicating with your bank when you are not. This is where certificates come in to play as they can be used to verify that the destination is who they say they are. In this case you bank. There are also some ways to abuse certificates to make them loo
Recommends M00kaw · 2013-04 · Information Security Stack Exchange · on “How safe is Tor from MITM/snooping attacks?”
Actually, Moxie Marlinspike created a tool called SSLStrip. He actually tested it on his TOR-node, and found that a lot of people didn't notice that the encryption was gone. His talk is worth a watch: Tricks on defeating SSL [this video] //M00kaw
Recommends Spencer D · 2014-09 · Information Security Stack Exchange · on “Facebook sometimes drops SSL. Why?”
Network speed bears no relation to this. As saint mentioned, it is likely the add-on. From an attack perspective, this would be possible by doing "SSL Stripping" during MiTM. SSL Stripping is the principle of the MiTM saying "switch all HTTPS links to HTTP." There's was an interesting defcon talk about this ( click here to see it [this video] ). In the presentation, the speaker, Moxie Marlinspike, showed that SSL Stripping was effective even on google. Since the talk, I believe google has ramped up their security to make itself only available using SSL; however, that just goes to show that at one point even Google was susceptible to this kind of attack. Edit: I see two other comments on your ques
Recommends mti2935 · 2020-06 · Information Security Stack Exchange · on “How to find vulnerabilities in a program by looking at it's source code”
See [this video] (start watching at around 30:00) to see how Moxie Marlinspike does it. In this example, he shows how he found a serious bug in the SSL implementation used by Mozilla. By exploiting the bug, he was able to launch a deadly attack that allowed him create a certificate on the fly that could be used to MITM any site, with the certificate being trusted by the browser.
Cites rook · 2011-09 · Information Security Stack Exchange · on “sslstrip vs. privoxy redirect rule on clients”
Yes, this Privoxy rule set will prevent just a plain SSLStrip attack. But it can't prevent against all attacks. Recently a certificate authority by the name of DigiNotar [LINK] was compromised. DigiNotar knew they have been comprised but failed to notify the public leading to Mozilla removing them as a trusted CA [LINK] . This hacker has claimed to compromised 4 other CAs [LINK] . These forged certificates have been used in iran [LINK] to MITM Gmail and Facebook. The author of SSLStrip, Moxie Marlenspike, was able to use it in conjunction with other attacks, such as null byte poisoning, to produce forged certificates. This attack was covered in More Tricks For Defeating SSL [this video] . In both
Cites rook · 2011-12 · Information Security Stack Exchange · on “Does HTTPS Everywhere defend me against sslsniff-like attacks?”
The short answer is: No, not always . I have studied this topic in depth and please read this entire post before forming a conclusion. SSLSniff is a proof of concept exploitation platform to leverage flaws in the PKI, such as vulnerabilities in OCSP [LINK] or the (ingenious) null-prefix certificate attack [LINK] . If you are using a fully patched system, and you understand what an SSL error means then you are immune to MOST (but not all) of these attacks without the need for HTTPS Everywhere. If you are not patched against the null-prefix certificate attack then the certificate will appear valid and HTTPS everywhere will be useless. If you don't understand what an SSL error means, then HTTPS
Cites Manishearth · 2013-04 · Information Security Stack Exchange · on “SSL Communication and Proxy”
Depends. In general, no. If the attacker launches a man-in-the-middle attack after HTTPS communication has already started, he can do nothing. If he launches the attack beforehand, he can do various things. For convenience, let's assume that the server in question is GMail. Pretend to be mail.google.com: This is a pretty transparent attack. The attacker cannot obtain a trusted signature for his SSL cert, and thus cannot pretend to be Google without throwing an error similar to this one [LINK] . If the client clicks through this; well, that's the client's fault. Catch you when you try HTTP: Some people enter [LINK] , which means that their browser will first try HTTP. Most HTTPS-only sites is
Cites David · 2013-07 · Information Security Stack Exchange · on “SSL - Null Prefix Attacks Still Possible?”
At DEFCON 17 (2009) Moxie Marlinspike gave a talk [this video] were he was able to use a malformed certificate signing request to get SSL certs signed for domains he doesn't own. The gist of it was that for the common name put something like [LINK] with \0 being a null byte. Is this attack still generally possible, of course you can probably find CAs that are still vulnerable but are the clients, particularly Microsoft's SSL stack?
Cites theking2 · 2013-11 · Information Security Stack Exchange · on “How can we trust PKI, for example, Verisign?”
We might trust Verisign, goDaddy, or Digicert. But a MITMA might render that trust useless as there are quite a few ways to let the browser and therefore the user believe he is in save waters. It is possible to spoof the certificate chain or spoof a revoked certificate as was demonstrated quite eloquently by Mike Marlinspike at Defcon17 ( [this video] ). So no, you can't trust VeriSign. Btw. VeriSign has been hacked in the few years before it was acquired my Symantec.