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 208a6012be3077d83df4475f32dd1b1446f3a02e)
Conflicts:
crypto/dsa/dsa_vrf.c
cause a denial of service. (CVE-2006-2940)
[Steve Henson, Bodo Moeller]
Fix ASN.1 parsing of certain invalid structures that can result
in a denial of service. (CVE-2006-2937) [Steve Henson]
Fix buffer overflow in SSL_get_shared_ciphers() function.
(CVE-2006-3738) [Tavis Ormandy and Will Drewry, Google Security Team]
Fix SSL client code which could crash if connecting to a
malicious SSLv2 server. (CVE-2006-4343)
[Tavis Ormandy and Will Drewry, Google Security Team]
timing attacks.
BN_FLG_EXP_CONSTTIME requests this algorithm, and this done by default for
RSA/DSA/DH private key computations unless
RSA_FLAG_NO_EXP_CONSTTIME/DSA_FLAG_NO_EXP_CONSTTIME/
DH_FLAG_NO_EXP_CONSTTIME is set.
Submitted by: Matthew D Wood
Reviewed by: Bodo Moeller
dh.h, dsa.h, ec.h, ecdh.h, ecdsa.h, rsa.h), as the opaque bignum types are
already declared in ossl_typ.h. Add explicit includes for bn.h in those C
files that need access to structure internals or API functions+macros.
changes are the fallout). As this could break source code that doesn't
directly include headers for interfaces it uses, changes to recursive
includes are covered by the OPENSSL_NO_DEPRECATED symbol. It's better to
define this when building and using openssl, and then adapt code where
necessary - this is how to stay current. However the mechanism exists for
the lethargic.
be) precompiled out in the API headers. This change is to ensure that if
it is defined when compiling openssl, the deprecated functions aren't
implemented either.
