This indicates an attack attempt against an Information Disclosure Vulnerability in OpenSSL.
The vulnerability is caused by an error when vulnerable application handles connections uses an AES CBC cipher. A MITM attacker may be able to exploit this to cause a padding attack to decrypt traffic.
OpenSSL Project OpenSSL prior to 1.0.2h
OpenSSL Project OpenSSL prior to 1.0.1t
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.