diff options
| author | Bernd Edlinger <bernd.edlinger@hotmail.de> | 2019-09-01 00:16:28 +0200 |
|---|---|---|
| committer | Matt Caswell <matt@openssl.org> | 2019-09-10 11:41:20 +0100 |
| commit | 08229ad838c50f644d7e928e2eef147b4308ad64 (patch) | |
| tree | 7cd83bda81488e16f3242e049968b1f595483ee6 /CHANGES | |
| parent | 7ff84d88036237dc36f4c2cf2dc814e4bf611084 (diff) | |
Fix a padding oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey
An attack is simple, if the first CMS_recipientInfo is valid but the
second CMS_recipientInfo is chosen ciphertext. If the second
recipientInfo decodes to PKCS #1 v1.5 form plaintext, the correct
encryption key will be replaced by garbage, and the message cannot be
decoded, but if the RSA decryption fails, the correct encryption key is
used and the recipient will not notice the attack.
As a work around for this potential attack the length of the decrypted
key must be equal to the cipher default key length, in case the
certifiate is not given and all recipientInfo are tried out.
The old behaviour can be re-enabled in the CMS code by setting the
CMS_DEBUG_DECRYPT flag.
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9777)
(cherry picked from commit 5840ed0cd1e6487d247efbc1a04136a41d7b3a37)
Diffstat (limited to 'CHANGES')
| -rw-r--r-- | CHANGES | 14 |
1 files changed, 14 insertions, 0 deletions
@@ -54,6 +54,20 @@ (CVE-2019-1547) [Billy Bob Brumley] + *) Fixed a padding oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey. + An attack is simple, if the first CMS_recipientInfo is valid but the + second CMS_recipientInfo is chosen ciphertext. If the second + recipientInfo decodes to PKCS #1 v1.5 form plaintext, the correct + encryption key will be replaced by garbage, and the message cannot be + decoded, but if the RSA decryption fails, the correct encryption key is + used and the recipient will not notice the attack. + As a work around for this potential attack the length of the decrypted + key must be equal to the cipher default key length, in case the + certifiate is not given and all recipientInfo are tried out. + The old behaviour can be re-enabled in the CMS code by setting the + CMS_DEBUG_DECRYPT flag. + [Bernd Edlinger] + *) Early start up entropy quality from the DEVRANDOM seed source has been improved for older Linux systems. The RAND subsystem will wait for /dev/random to be producing output before seeding from /dev/urandom. |