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 xxxterm 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. This is the result for xxxterm: /xxxterm-1.10.0/xxxterm.c have problems. Host name verification missing We provide this result to help developers to locate the problem faster. To verify the result: 一. Hostname check 1.configure /etc/hosts in order to simulate DNS hijack 42.62.48.90 www.facebook.com # 42.62.48.90 is the ip of i.mi.com 2. visit the website https://www.facebook.com with xxxterm 3. result : connecting succeed without any warning!!! The fetch succeeded, indicating xxxterm 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 xxxterm to visit any https website, such as https://www.youtube.com. 3. result : succeed without any warning!! The fetch succeeded again and no warning was given, indicating xxxterm didn't check whether the certificate expired or not. I am running xxxterm 1.11.3-1.2 in ubuntu 14.04 LTS. I have save the SSL connecting packages and upload these wireshark files. for more information about the importance of checking hostname: see http://people.stfx.ca/x2011/x2011ucj/SSL/p38-georgiev.pdf Thanks. ** Affects: xxxterm (Ubuntu) Importance: Undecided Status: New ** Tags: ssl ** Attachment added: "wireshark ssl connecting packages" https://bugs.launchpad.net/bugs/1378617/+attachment/4227990/+files/xxxterm.zip ** 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/1378617 Title: xxxterm has SSL security problems To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xxxterm/+bug/1378617/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
