Fix for Klima-Pokorny-Rosa attack on RSA in SSL/TLS, see

http://marc.theaimsgroup.com/?l=bugtraq&m=104811162730834&w=2

2 files changed, 24 insertions, 26 deletions

diff --git a/src/lib/libssl/s3_srvr.c b/src/lib/libssl/s3_srvr.c
index 2e1b0eb892..a2c17f2950 100644
--- a/src/lib/libssl/s3_srvr.c
+++ b/src/lib/libssl/s3_srvr.c
@@ -1441,7 +1441,7 @@ static int ssl3_get_client_key_exchange(SSL *s)
                 if (i != SSL_MAX_MASTER_KEY_LENGTH)
                         {
                         al=SSL_AD_DECODE_ERROR;
-                        SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT);
+                        /* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT); */
                         }
 
                 if ((al == -1) && !((p[0] == (s->client_version>>8)) && (p[1] == (s->client_version & 0xff))))
@@ -1457,30 +1457,29 @@ static int ssl3_get_client_key_exchange(SSL *s)
                                 (p[0] == (s->version>>8)) && (p[1] == (s->version & 0xff))))
                                 {
                                 al=SSL_AD_DECODE_ERROR;
-                                SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
-                                goto f_err;
+                                /* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER); */
+
+                                /* The Klima-Pokorny-Rosa extension of Bleichenbacher's attack
+                                 * (http://eprint.iacr.org/2003/052/) exploits the version
+                                 * number check as a "bad version oracle" -- an alert would
+                                 * reveal that the plaintext corresponding to some ciphertext
+                                 * made up by the adversary is properly formatted except
+                                 * that the version number is wrong.  To avoid such attacks,
+                                 * we should treat this just like any other decryption error. */
+                                p[0] = (char)(int) "CAN-2003-0131 patch 2003-03-20";
                                 }
                         }
 
                 if (al != -1)
                         {
-#if 0
-                        goto f_err;
-#else
                         /* Some decryption failure -- use random value instead as countermeasure
                          * against Bleichenbacher's attack on PKCS #1 v1.5 RSA padding
-                         * (see RFC 2246, section 7.4.7.1).
-                         * But note that due to length and protocol version checking, the
-                         * attack is impractical anyway (see section 5 in D. Bleichenbacher:
-                         * "Chosen Ciphertext Attacks Against Protocols Based on the RSA
-                         * Encryption Standard PKCS #1", CRYPTO '98, LNCS 1462, pp. 1-12).
-                         */
+                         * (see RFC 2246, section 7.4.7.1). */
                         ERR_clear_error();
                         i = SSL_MAX_MASTER_KEY_LENGTH;
                         p[0] = s->client_version >> 8;
                         p[1] = s->client_version & 0xff;
                         RAND_pseudo_bytes(p+2, i-2); /* should be RAND_bytes, but we cannot work around a failure */
-#endif
                         }
         
                 s->session->master_key_length=
diff --git a/src/lib/libssl/src/ssl/s3_srvr.c b/src/lib/libssl/src/ssl/s3_srvr.c
index 2e1b0eb892..a2c17f2950 100644
--- a/src/lib/libssl/src/ssl/s3_srvr.c
+++ b/src/lib/libssl/src/ssl/s3_srvr.c
@@ -1441,7 +1441,7 @@ static int ssl3_get_client_key_exchange(SSL *s)
                 if (i != SSL_MAX_MASTER_KEY_LENGTH)
                         {
                         al=SSL_AD_DECODE_ERROR;
-                        SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT);
+                        /* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT); */
                         }
 
                 if ((al == -1) && !((p[0] == (s->client_version>>8)) && (p[1] == (s->client_version & 0xff))))
@@ -1457,30 +1457,29 @@ static int ssl3_get_client_key_exchange(SSL *s)
                                 (p[0] == (s->version>>8)) && (p[1] == (s->version & 0xff))))
                                 {
                                 al=SSL_AD_DECODE_ERROR;
-                                SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
-                                goto f_err;
+                                /* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER); */
+
+                                /* The Klima-Pokorny-Rosa extension of Bleichenbacher's attack
+                                 * (http://eprint.iacr.org/2003/052/) exploits the version
+                                 * number check as a "bad version oracle" -- an alert would
+                                 * reveal that the plaintext corresponding to some ciphertext
+                                 * made up by the adversary is properly formatted except
+                                 * that the version number is wrong.  To avoid such attacks,
+                                 * we should treat this just like any other decryption error. */
+                                p[0] = (char)(int) "CAN-2003-0131 patch 2003-03-20";
                                 }
                         }
 
                 if (al != -1)
                         {
-#if 0
-                        goto f_err;
-#else
                         /* Some decryption failure -- use random value instead as countermeasure
                          * against Bleichenbacher's attack on PKCS #1 v1.5 RSA padding
-                         * (see RFC 2246, section 7.4.7.1).
-                         * But note that due to length and protocol version checking, the
-                         * attack is impractical anyway (see section 5 in D. Bleichenbacher:
-                         * "Chosen Ciphertext Attacks Against Protocols Based on the RSA
-                         * Encryption Standard PKCS #1", CRYPTO '98, LNCS 1462, pp. 1-12).
-                         */
+                         * (see RFC 2246, section 7.4.7.1). */
                         ERR_clear_error();
                         i = SSL_MAX_MASTER_KEY_LENGTH;
                         p[0] = s->client_version >> 8;
                         p[1] = s->client_version & 0xff;
                         RAND_pseudo_bytes(p+2, i-2); /* should be RAND_bytes, but we cannot work around a failure */
-#endif
                         }
         
                 s->session->master_key_length=