A recent attack in Chile highlights a dangerous blind spot in Microsoft 365 security: ghost service accounts. According to Dark Reading, even if an organization locks down employee accounts, forgotten and lost service accounts can still undo the entire M365 environment. These accounts often carry high privileges and are not subject to the same monitoring as user accounts, making them an attractive target for attackers.
The source emphasizes that the risk is not from sophisticated exploits but from basic hygiene failures. Service accounts are frequently created for integrations, automation, or legacy applications, then left behind when the project ends or the vendor changes. Because no one remembers they exist, they are rarely rotated, monitored, or disabled.
To mitigate this threat, organizations need to treat service accounts as first-class security objects. That means maintaining a complete inventory, applying least-privilege access, and regularly reviewing and removing accounts that are no longer needed. The Chilean case is a reminder that attackers will look for the path of least resistance, and an abandoned service account can be exactly that. The source does not offer a different view; it focuses solely on this overlooked risk and its consequences.