Fix various certificate fingerprint issues.

By using non-DER or invalid encodings outside the signed portion of a
certificate the fingerprint can be changed without breaking the signature.
Although no details of the signed portion of the certificate can be changed
this can cause problems with some applications: e.g. those using the
certificate fingerprint for blacklists.

1. Reject signatures with non zero unused bits.

If the BIT STRING containing the signature has non zero unused bits reject
the signature. All current signature algorithms require zero unused bits.

2. Check certificate algorithm consistency.

Check the AlgorithmIdentifier inside TBS matches the one in the
certificate signature. NB: this will result in signature failure
errors for some broken certificates.

3. Check DSA/ECDSA signatures use DER.

Reencode DSA/ECDSA signatures and compare with the original received
signature. Return an error if there is a mismatch.

This will reject various cases including garbage after signature
(thanks to Antti Karjalainen and Tuomo Untinen from the Codenomicon CROSS
program for discovering this case) and use of BER or invalid ASN.1 INTEGERs
(negative or with leading zeroes).

CVE-2014-8275
Reviewed-by: Emilia Käsper <emilia@openssl.org>
(cherry picked from commit 684400ce192dac51df3d3e92b61830a6ef90be3e)

Conflicts:
	CHANGES
	crypto/dsa/dsa_asn1.c

diff --git a/CHANGES b/CHANGES
index 7c96384bc0b4734020184b7de4e182551ed296d6..8e8646e674c96c99d8b38e51d52a804203c54050 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,7 +4,42 @@
 
  Changes between 1.0.0o and 1.0.0p [xx XXX xxxx]
 
-  *)
+  *) Fix various certificate fingerprint issues.
+
+     By using non-DER or invalid encodings outside the signed portion of a
+     certificate the fingerprint can be changed without breaking the signature.
+     Although no details of the signed portion of the certificate can be changed
+     this can cause problems with some applications: e.g. those using the
+     certificate fingerprint for blacklists.
+
+     1. Reject signatures with non zero unused bits.
+
+     If the BIT STRING containing the signature has non zero unused bits reject
+     the signature. All current signature algorithms require zero unused bits.
+
+     2. Check certificate algorithm consistency.
+
+     Check the AlgorithmIdentifier inside TBS matches the one in the
+     certificate signature. NB: this will result in signature failure
+     errors for some broken certificates.
+
+     Thanks to Konrad Kraszewski from Google for reporting this issue.
+
+     3. Check DSA/ECDSA signatures use DER.
+
+     Reencode DSA/ECDSA signatures and compare with the original received
+     signature. Return an error if there is a mismatch.
+
+     This will reject various cases including garbage after signature
+     (thanks to Antti Karjalainen and Tuomo Untinen from the Codenomicon CROSS
+     program for discovering this case) and use of BER or invalid ASN.1 INTEGERs
+     (negative or with leading zeroes).
+
+     Further analysis was conducted and fixes were developed by Stephen Henson
+     of the OpenSSL core team.
+
+     (CVE-2014-8275)
+     [Steve Henson]
 
  Changes between 1.0.0n and 1.0.0o [15 Oct 2014]
 

diff --git a/crypto/asn1/a_verify.c b/crypto/asn1/a_verify.c
index 097ec813ac24dbb42956a037ab5ecaab8fa3f995..a75c8c9b5ffd59706643b239e257f9f2bb7a1cb3 100644 (file)
--- a/crypto/asn1/a_verify.c
+++ b/crypto/asn1/a_verify.c
@@ -90,6 +90,12 @@ int ASN1_verify(i2d_of_void *i2d, X509_ALGOR *a, ASN1_BIT_STRING *signature,
                ASN1err(ASN1_F_ASN1_VERIFY,ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
                goto err;
                }
+
+       if (signature->type == V_ASN1_BIT_STRING && signature->flags & 0x7)
+               {
+               ASN1err(ASN1_F_ASN1_VERIFY, ASN1_R_INVALID_BIT_STRING_BITS_LEFT);
+               goto err;
+               }
        
        inl=i2d(data,NULL);
        buf_in=OPENSSL_malloc((unsigned int)inl);
@@ -142,6 +148,12 @@ int ASN1_item_verify(const ASN1_ITEM *it, X509_ALGOR *a, ASN1_BIT_STRING *signat
                return -1;
                }
 
+       if (signature->type == V_ASN1_BIT_STRING && signature->flags & 0x7)
+               {
+               ASN1err(ASN1_F_ASN1_VERIFY, ASN1_R_INVALID_BIT_STRING_BITS_LEFT);
+               return -1;
+               }
+
        EVP_MD_CTX_init(&ctx);
 
        /* Convert signature OID into digest and public key OIDs */

diff --git a/crypto/dsa/dsa_vrf.c b/crypto/dsa/dsa_vrf.c
index 226a75ff3f27ade628dfae661b4fe35dc87a626a..9a6905bfafffd1841f10d0b487fee6082e21b488 100644 (file)
--- a/crypto/dsa/dsa_vrf.c
+++ b/crypto/dsa/dsa_vrf.c
@@ -77,13 +77,25 @@ int DSA_verify(int type, const unsigned char *dgst, int dgst_len,
             const unsigned char *sigbuf, int siglen, DSA *dsa)
        {
        DSA_SIG *s;
+       const unsigned char *p = sigbuf;
+       unsigned char *der = NULL;
+       int derlen = -1;
        int ret=-1;
 
        s = DSA_SIG_new();
        if (s == NULL) return(ret);
-       if (d2i_DSA_SIG(&s,&sigbuf,siglen) == NULL) goto err;
+       if (d2i_DSA_SIG(&s,&p,siglen) == NULL) goto err;
+       /* Ensure signature uses DER and doesn't have trailing garbage */
+       derlen = i2d_DSA_SIG(s, &der);
+       if (derlen != siglen || memcmp(sigbuf, der, derlen))
+               goto err;
        ret=DSA_do_verify(dgst,dgst_len,s,dsa);
 err:
+       if (derlen > 0)
+               {
+               OPENSSL_cleanse(der, derlen);
+               OPENSSL_free(der);
+               }
        DSA_SIG_free(s);
        return(ret);
        }

diff --git a/crypto/ecdsa/ecs_vrf.c b/crypto/ecdsa/ecs_vrf.c
index ef9acf7b610284d697bcea815061ef29a67fce0e..2836efe5eff228bf9ef0e707f723f1b6e8ba937e 100644 (file)
--- a/crypto/ecdsa/ecs_vrf.c
+++ b/crypto/ecdsa/ecs_vrf.c
@@ -57,6 +57,7 @@
  */
 
 #include "ecs_locl.h"
+#include "cryptlib.h"
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif
@@ -84,13 +85,25 @@ int ECDSA_verify(int type, const unsigned char *dgst, int dgst_len,
                const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
        {
        ECDSA_SIG *s;
+       const unsigned char *p = sigbuf;
+       unsigned char *der = NULL;
+       int derlen = -1;
        int ret=-1;
 
        s = ECDSA_SIG_new();
        if (s == NULL) return(ret);
-       if (d2i_ECDSA_SIG(&s, &sigbuf, sig_len) == NULL) goto err;
+       if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) goto err;
+       /* Ensure signature uses DER and doesn't have trailing garbage */
+       derlen = i2d_ECDSA_SIG(s, &der);
+       if (derlen != sig_len || memcmp(sigbuf, der, derlen))
+               goto err;
        ret=ECDSA_do_verify(dgst, dgst_len, s, eckey);
 err:
+       if (derlen > 0)
+               {
+               OPENSSL_cleanse(der, derlen);
+               OPENSSL_free(der);
+               }
        ECDSA_SIG_free(s);
        return(ret);
        }

diff --git a/crypto/x509/x_all.c b/crypto/x509/x_all.c
index 8ec88c215a4f6c5b79e5a96c27076bb1d333be33..3571bf03fe828f2617fa16df6c8b3e0811047fe5 100644 (file)
--- a/crypto/x509/x_all.c
+++ b/crypto/x509/x_all.c
@@ -72,6 +72,8 @@
 
 int X509_verify(X509 *a, EVP_PKEY *r)
        {
+       if (X509_ALGOR_cmp(a->sig_alg, a->cert_info->signature))
+               return 0;
        return(ASN1_item_verify(ASN1_ITEM_rptr(X509_CINF),a->sig_alg,
                a->signature,a->cert_info,r));
        }