The detection rule named "First Time Seen Removable Device" identifies newly connected removable devices in Windows environments by monitoring registry modification events specific to USB storage devices. The rule utilizes event data from multiple indices including endpoint registry logs and security events from various sources such as Winlogbeat and Microsoft Defender for Endpoint. It aims to provide early indicators of potential data exfiltration activities as the presence of new removable devices could signify unauthorized access by adversaries aiming to transfer sensitive data or introduce malware using these devices. The rule triggers on registry changes where the "FriendlyName" for devices is updated in a path associated with USB storage. This enables analysts to perform targeted investigations into user activity and file transfers associated with newly detected devices. While the detection itself is not inherently malicious, closely monitoring such events can lead to the identification of suspicious behavior, particularly during initial access and potential exfiltration attempts. The risk score assigned to this rule is low (21), indicating a lower probability of a true positive but still warranting investigation.