Definition: Csgate: "Cyber Security Group A" refers to a group within a large corporation or organization that was involved in the compromise of sensitive information related to cyber security systems, known as "cybersecurity breaches". The term describes an organization or individual who has violated the principle of trust and integrity by failing to disclose known vulnerabilities or weaknesses in their cybersecurity measures. It's often used when referring to major breaches involving millions or even billions of dollars in losses.