*** This bug is a security vulnerability *** Public security bug reported:
Recently, we are trying to find SSL security problems by static analysis. For example, as we all know, 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. And static analysis is a way of finding whether the APIs are called correctly. Now, we find some SSL problems in citadel-client: 1. miss hostname check when verify x509 certificate 2. miss expired time check when verify x509 certificate More specifically , we can take function SSL_CTX_set_verify() 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 at first. Then use X509 APIs or self-define function to verify the certificate we get. If the source code does not match this model, then we can deduce this code is vulnerable. And other APIs have similar problems. To verify the result we make, we attack the software manually. we take expired time check for example : 1. change the system time to 2200 to guarantee the certificate to be expired. 2. use citadel-client to connect to a citadel server with ssl 3. result:succeed!! The fetch succeeded again and no warning was given, indicating the software didn't check whether the certificate expired. PS: for more information, you can see the paper: http://people.stfx.ca/x2011/x2011ucj/SSL/p38-georgiev.pdf and more details you can contact with us, we will be very glad for your responce. Thanks. ** Affects: citadel-client (Ubuntu) Importance: Undecided Status: New ** Information type changed from Private Security to Public Security -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1380449 Title: citadel-client have some ssl security problems To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/citadel-client/+bug/1380449/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
