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>
Tue, 3 Jun 2014 15:30:23 +0000 (16:30 +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.

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

index 7caabf3..af29600 100644 (file)
@@ -491,6 +491,7 @@ int ssl3_connect(SSL *s)
                case SSL3_ST_CR_FINISHED_A:
                case SSL3_ST_CR_FINISHED_B:
 
                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;
                        ret=ssl3_get_finished(s,SSL3_ST_CR_FINISHED_A,
                                SSL3_ST_CR_FINISHED_B);
                        if (ret <= 0) goto end;
@@ -777,6 +778,7 @@ 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;
                }
                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 */
            s->hit=1;
            }
        else    /* a miss or crap from the other end */
index 169f235..6caa3bb 100644 (file)
@@ -1166,6 +1166,15 @@ start:
                        goto f_err;
                        }
 
                        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)
                rr->length=0;
 
                if (s->msg_callback)
index 06c7b00..fcc97f3 100644 (file)
@@ -523,6 +523,7 @@ int ssl3_accept(SSL *s)
                case SSL3_ST_SR_CERT_VRFY_A:
                case SSL3_ST_SR_CERT_VRFY_B:
 
                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;
                        /* we should decide if we expected this one */
                        ret=ssl3_get_cert_verify(s);
                        if (ret <= 0) goto end;
@@ -533,6 +534,7 @@ int ssl3_accept(SSL *s)
 
                case SSL3_ST_SR_FINISHED_A:
                case SSL3_ST_SR_FINISHED_B:
 
                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;
                        ret=ssl3_get_finished(s,SSL3_ST_SR_FINISHED_A,
                                SSL3_ST_SR_FINISHED_B);
                        if (ret <= 0) goto end;
index 3aab080..de5e559 100644 (file)
@@ -333,6 +333,7 @@ typedef struct ssl3_buffer_st
 #define SSL3_FLAGS_DELAY_CLIENT_FINISHED       0x0002
 #define SSL3_FLAGS_POP_BUFFER                  0x0004
 #define TLS1_FLAGS_TLS_PADDING_BUG             0x0008
 #define SSL3_FLAGS_DELAY_CLIENT_FINISHED       0x0002
 #define SSL3_FLAGS_POP_BUFFER                  0x0004
 #define TLS1_FLAGS_TLS_PADDING_BUG             0x0008
+#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
  
 /* SSL3_FLAGS_SGC_RESTART_DONE is set when we
  * restart a handshake because of MS SGC and so prevents us