- djm@cvs.openbsd.org 2014/01/09 23:26:48

     [sshconnect.c sshd.c]
     ban clients/servers that suffer from SSH_BUG_DERIVEKEY, they are ancient,
     deranged and might make some attacks on KEX easier; ok markus@

1 files changed, 7 insertions, 2 deletions

diff --git a/sshd.c b/sshd.c
index 87795bea5..60b416e30 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.413 2013/12/30 23:52:28 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.414 2014/01/09 23:26:48 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -502,9 +502,14 @@ sshd_exchange_identification(int sock_in, int sock_out)
                     get_remote_ipaddr(), client_version_string);
                 cleanup_exit(255);
         }
-        if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
+        if ((datafellows & SSH_BUG_RSASIGMD5) != 0) {
                 logit("Client version \"%.100s\" uses unsafe RSA signature "
                     "scheme; disabling use of RSA keys", remote_version);
+        }
+        if ((datafellows & SSH_BUG_DERIVEKEY) != 0) {
+                fatal("Client version \"%.100s\" uses unsafe key agreement; "
+                    "refusing connection", remote_version);
+        }
 
         mismatch = 0;
         switch (remote_major) {