In NTFS file system analysis, explain how analyzing file slack space can contribute to an investigation.

In NTFS file system analysis, analyzing file slack space can contribute to an investigation by revealing hidden or residual data. File slack space is the unused area within a file's allocated storage space on a hard drive. This occurs because files are typically stored in clusters, which are fixed-size units of storage. If a file's size is not an exact multiple of the cluster size, the remaining portion of the last cluster remains unused, creating slack space. There are two types of slack space: file slack and volume slack. File slack is the space from the end of the file’s data to the end of the cluster. Volume slack is the space from the end of the file system to the end of the partition. This slack space can contain remnants of previously deleted files, fragments of data from other applications, or even intentionally hidden data. For example, a user might try to conceal sensitive information by copying it into the slack space of a seemingly innocuous file. By examining file slack space using forensic tools, investigators can uncover these hidden fragments of data, potentially revealing deleted files, passwords, encryption keys, or other evidence relevant to the investigation. Analyzing slack space requires specialized tools that can read the raw data from the disk at the cluster level, as this information is not normally accessible through standard file system operations. This technique is especially valuable when users attempt to hide data or when recovering deleted files proves challenging through conventional methods.