Final answer:
The HeartBleed bug is a security vulnerability in OpenSSL that allowed an attacker to read sensitive information from systems using vulnerable versions of OpenSSL.
Step-by-step explanation:
The HeartBleed bug is a security vulnerability that affected the OpenSSL software library, which is widely used to implement the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. It allowed an attacker to read the memory of the systems using the vulnerable versions of OpenSSL, potentially exposing sensitive information such as encryption keys, passwords, and other confidential data.
This bug had the potential to take an encrypted communication stream and offer a way to decrypt it, compromising the security of the communication. It was not specific to any operating system and affected a wide range of systems using the vulnerable versions of OpenSSL.