When a penetration tester captures screen images that include hashes from a domain controller, obscuring parts of these images before saving is crucial to maintain the confidentiality of sensitive data. Hashes can be considered sensitive information as they represent a form of digital identity for users within an organization. Revealing these hashes in full could lead to unauthorized access if the hashes were to be cracked or otherwise misused by malicious actors. By partially obscuring the images, the penetration tester ensures that the data remains confidential and reduces the risk of compromising user accounts and the integrity of the organization's security posture.