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Fix for CVE-2014-0224

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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.
This commit is contained in:
Dr. Stephen Henson 2014-05-16 12:49:48 +01:00
parent 82ba68c42d
commit 410a49a4fa
4 changed files with 14 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
ssl/s3_clnt.c
View file

@ -491,6 +491,7 @@ 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;
@ -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;
}
s->s3->flags |= SSL3_FLAGS_CCS_OK;
s->hit=1;
}
else /* a miss or crap from the other end */

9
ssl/s3_pkt.c
View file

@ -1166,6 +1166,15 @@ 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)

2
ssl/s3_srvr.c
View file

@ -523,6 +523,7 @@ 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;
@ -533,6 +534,7 @@ 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;

1
ssl/ssl3.h
View 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_CCS_OK 0x0080
/* SSL3_FLAGS_SGC_RESTART_DONE is set when we
* restart a handshake because of MS SGC and so prevents us