PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys

Issue Summary: The PKCS#12 file processing fails to perform sufficient input

validation for files that use Password-Based Message Authentication Code 1

(PBMAC1) integrity mechanism allowing a certificate and private key forgery.

Impact Summary: An attacker impersonating a user can cause a service reading

PKCS#12 files to accept forged certificates and private keys with a 1 in 256

probability.

If a service accepting PKCS#12 files is using passwords for authenticating

the received files, the attacker can create unencrypted PKCS#12 files that

use PBMAC1 authentication that specifies an HMAC key of only one byte, allowing

them to craft a file that will be accepted with a 1 in 256 probability.

That would then cause the service to accept a certificate and private key

controlled by the attacker.

The FIPS modules are not affected by this issue, as the affected code is

outside the OpenSSL FIPS module boundary.