What characterizes a pre-existing compromise?

A pre-existing compromise is characterized by unauthorized access that has been obtained and potentially sold or shared with another user. This situation implies that an attacker has already penetrated a system, which can lead to further exploitation of network resources and sensitive information. The core concept is that the integrity of the network or system has been breached prior to detection, allowing malicious actors to maneuver undetected within the system.

The other options do not align with the concept of a pre-existing compromise. A security breach detected immediately refers to active incidents rather than incidents that have already occurred without detection. Data stored in a secure network implies that the data is protected and not compromised. A temporary access point set up for testing suggests a legitimate and controlled testing scenario, which is not related to unauthorized access or compromise.