Public bug reported: Hostname verification is an important step when verifying X509 certificates, however, people tend to miss the step or to misunderstand the APIs when using SSL/TLS, which might cause severe man in the middle attack and break the entire TLS mechanism.
We believe that scrollz didn't check whether the hostname matches the name in the SSL certificate and the expired date of the certificate. We found the vulnerability by static analysis, typically, a process of verification involves calling a chain of API, and we can deduce whether the communication process is vulnerable by detecting whether the function call process matches a certain model. For example, when using OPENSSL, if we call SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_NONE, null), we should verify the certificate by calling the function SSL_get_peer_certificate() to get the certificate. If the source code does not match this model, then we can deduce this code is vulnerable. What’ more , Gnutls is the same as Openssl. Static analysis result : /scrollz-2.1/source/server.c login_to_server() have problems. We provide this result to help developers to locate the problem faster. To verify the result: 一.Hostname verification 1. write the file /etc/hosts in order to simulate DNS hijack: 64.32.24.176 irc.mibbit.net 46.137.23.30 chat.freenode.net (PS：exchange the ip between these two irc servers) 2. connecting chat.freenode.net with scrollz /server -ssl irc.mibbit.net:6697 3. result : we connected irc.mibbit.net!! The fetch succeeded, indicating srcollz didn't check the hostname against the signee of the certificate. 二. Also for expired time check, 1. change the system time to 2200 to guarantee the certificate to be expired. 2. run scrollz to connect a normal irc server, such as irc.mibbit.net(46.137.12.30) 3. result : connect succeed!! The fetch succeeded again and no warning was given, indicating scrollz didn't check whether the certificate expired or not. I am running scrollz 2.1-1.1 in ubuntu 14.04 LTS. for more information about the importance of checking hostname: see http://people.stfx.ca/x2011/x2011ucj/SSL/p38-georgiev.pdf Thanks. ** Affects: scrollz (Ubuntu) Importance: Undecided Status: New ** Tags: ssl ** Information type changed from Private Security to Public -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1376595 Title: X509 certificate verification problem To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/scrollz/+bug/1376595/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
