Hi Bartosz, First of all, thank you for volunteering to check this out.
If client trusts a CA which is not universally trusted, is it possible to find that CA information within the client ? If yes we can use the same CA to check the certificates, right ? On Tue, Jun 4, 2013 at 5:07 PM, Bartosz Brachaczek <b.brachac...@gmail.com>wrote: > Hi, > > Simply using SSL_get_verify_result() is not a solution here, as it > returns X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY when connecting > to the proprietary servers on my system (I assume I am not being > attacked, you might want to confirm it yourself). > > But checking which certificates are accepted by the proprietary client > should be straightforward, as the current version of it is written in > XUL and uses xulrunner's/gecko's methods of verifying certificates. I > can volunteer to check this. If it turns out that the proprietary > client trusts a CA that is not universally trusted, we might want to > trust the same one when connecting to the Gadu-Gadu network in > libgadu. > > Bartosz > > PS. I'm attaching a patch so you can easily check what does > SSL_get_verify_result() return on your system. > > diff --git a/src/events.c b/src/events.c > index 3f401e9..2cb104c 100644 > --- a/src/events.c > +++ b/src/events.c > @@ -1145,6 +1145,10 @@ static gg_action_t > gg_handle_tls_negotiation(struct gg_session *sess, struct gg_ > > X509_NAME_oneline(X509_get_issuer_name(peer), buf, sizeof(buf)); > gg_debug_session(sess, GG_DEBUG_MISC, "// cert issuer: %s\n", > buf); > + > + long res = SSL_get_verify_result(GG_SESSION_OPENSSL(sess)); > + if (res != X509_V_OK) > + gg_debug_session(sess, GG_DEBUG_MISC, "// WARNING! > unable to verify peer certificate! res=%ld\n", res); > } > > sess->state = next_state; > > > 2013/6/4 Radhesh Krishnan K <radheshkrishn...@gmail.com>: > > Hi Wojtek, > > > > Sorry, I have a doubt. I would like to know how certificate validation is > > performed in the proprietary protocol and why something similar cannot be > > performed in this case? > > > > > > > > On Tue, Jun 4, 2013 at 4:41 AM, Wojtek Kaniewski <wojte...@toxygen.net> > > wrote: > >> > >> Dnia 2013-06-02, nie o godzinie 19:02 +0530, Radhesh Krishnan K pisze: > >> > I would like to report a security bug in libgadu. libgadu is using > >> > openSSL library for creating secure connections. > >> > (...) > >> > So the product using libgadu will be vulnerable to man-in-the-middle > >> > attack. > >> > >> It was rather a conscious decision. Since libgadu is a > >> reverse-engineered implementation of a proprietary protocol, we have no > >> control over the certificates used for SSL connections. We don't know > >> which certificates will be accepted or rejected by the original client, > >> so there is no reliable way to verify their validity in libgadu. But > >> since you mentioned it, I guess we should at least add a note to the > >> documentation. > >> > >> Regards, > >> Wojtek > >> > >> > > > > > > > > -- > > > > > > > > > > Regards, > > Radhesh Krishnan K. > > > > _______________________________________________ > > libgadu-devel mailing list > > email@example.com > > http://lists.ziew.org/mailman/listinfo/libgadu-devel > > > _______________________________________________ > libgadu-devel mailing list > firstname.lastname@example.org > http://lists.ziew.org/mailman/listinfo/libgadu-devel > -- Regards, Radhesh Krishnan K.
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