title: 0-byte record padding oracle
description: If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).
problem types: Padding Oracle
affected:
{
product: OpenSSL
vendor: OpenSSL
versions:
status: affected, version: Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q)
}
metrics:
other: [
content: {'lang': 'eng', 'url': 'https://www.openssl.org/policies/secpolicy.html#Moderate', 'value': 'Moderate'}
type: unknown
]