Fix for CVE-2014-0224
authorDr. Stephen Henson <steve@openssl.org>
Fri, 16 May 2014 11:49:48 +0000 (12:49 +0100)
committerDr. Stephen Henson <steve@openssl.org>
Thu, 5 Jun 2014 12:22:42 +0000 (13:22 +0100)
Only accept change cipher spec when it is expected instead of at any
time. This prevents premature setting of session keys before the master
secret is determined which an attacker could use as a MITM attack.

Thanks to KIKUCHI Masashi (Lepidum Co. Ltd.) for reporting this issue
and providing the initial fix this patch is based on.
(cherry picked from commit bc8923b1ec9c467755cd86f7848c50ee8812e441)

ssl/s3_clnt.c
ssl/s3_pkt.c
ssl/s3_srvr.c
ssl/ssl3.h

index 5fc9069..34efff8 100644 (file)
@@ -599,6 +599,7 @@ int ssl3_connect(SSL *s)
                case SSL3_ST_CR_FINISHED_A:
                case SSL3_ST_CR_FINISHED_B:
 
+                       s->s3->flags |= SSL3_FLAGS_CCS_OK;
                        ret=ssl3_get_finished(s,SSL3_ST_CR_FINISHED_A,
                                SSL3_ST_CR_FINISHED_B);
                        if (ret <= 0) goto end;
@@ -1051,6 +1052,7 @@ int ssl3_get_server_hello(SSL *s)
                SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);
                goto f_err;
                }
+           s->s3->flags |= SSL3_FLAGS_CCS_OK;
            s->hit=1;
            }
        else    /* a miss or crap from the other end */
index 34eb2b4..fb9720f 100644 (file)
@@ -1593,6 +1593,15 @@ start:
                        goto f_err;
                        }
 
+               if (!(s->s3->flags & SSL3_FLAGS_CCS_OK))
+                       {
+                       al=SSL_AD_UNEXPECTED_MESSAGE;
+                       SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_CCS_RECEIVED_EARLY);
+                       goto f_err;
+                       }
+
+               s->s3->flags &= ~SSL3_FLAGS_CCS_OK;
+
                rr->length=0;
 
                if (s->msg_callback)
index 72fd3e4..31bfe47 100644 (file)
@@ -708,6 +708,7 @@ int ssl3_accept(SSL *s)
                case SSL3_ST_SR_CERT_VRFY_A:
                case SSL3_ST_SR_CERT_VRFY_B:
 
+                       s->s3->flags |= SSL3_FLAGS_CCS_OK;
                        /* we should decide if we expected this one */
                        ret=ssl3_get_cert_verify(s);
                        if (ret <= 0) goto end;
@@ -735,6 +736,7 @@ int ssl3_accept(SSL *s)
 
                case SSL3_ST_SR_FINISHED_A:
                case SSL3_ST_SR_FINISHED_B:
+                       s->s3->flags |= SSL3_FLAGS_CCS_OK;
                        ret=ssl3_get_finished(s,SSL3_ST_SR_FINISHED_A,
                                SSL3_ST_SR_FINISHED_B);
                        if (ret <= 0) goto end;
@@ -805,7 +807,10 @@ int ssl3_accept(SSL *s)
                                s->s3->tmp.next_state=SSL3_ST_SR_FINISHED_A;
 #else
                                if (s->s3->next_proto_neg_seen)
+                                       {
+                                       s->s3->flags |= SSL3_FLAGS_CCS_OK;
                                        s->s3->tmp.next_state=SSL3_ST_SR_NEXT_PROTO_A;
+                                       }
                                else
                                        s->s3->tmp.next_state=SSL3_ST_SR_FINISHED_A;
 #endif
index 8bd201e..82dd76c 100644 (file)
@@ -428,6 +428,7 @@ typedef struct ssl3_buffer_st
 #define TLS1_FLAGS_TLS_PADDING_BUG             0x0008
 #define TLS1_FLAGS_SKIP_CERT_VERIFY            0x0010
 #define TLS1_FLAGS_KEEP_HANDSHAKE              0x0020
+#define SSL3_FLAGS_CCS_OK                      0x0080
  
 /* SSL3_FLAGS_SGC_RESTART_DONE is set when we
  * restart a handshake because of MS SGC and so prevents us