The Forensic Significance of the NTFS $I30 File

Shellmates Club
3 min readJul 29, 2023

written by Chiheb Chahine YAICI

Introduction

The NTFS file system, the default file system employed by the Windows operating system, relies on a specialized file called the $I30 File to fulfill several crucial functions related to file and directory management. This article explores the technical intricacies of the $I30 File and its paramount role in forensic analysis, providing an index of all file names and directories on an NTFS volume.

Overview of the $I30 File

Each folder within the NTFS file system contains its own $I30 File, and the records within this file are dynamically updated whenever changes occur to the content of the associated directory.

Efficiency Enhancement:

The $I30 File significantly enhances the performance of the file system by facilitating rapid retrieval of files and directories. Unlike conventional methods that necessitate scanning the entire logical volume, the $I30 File enables swift access, ensuring efficient operations when visiting folders.

Integrity Preservation:

One of the core utilities of the $I30 File is to preserve the integrity of volume files. By retaining modification entries, any discrepancies or anomalies within the file system can be detected and remedied.

Details of the $I30 File

The $I30 File houses its entries in the form of $FILE_NAME attribute types, which serve as special NTFS attributes to store essential information about files and directories. These attributes include:

  1. Full filename
  2. Parent directory
  3. File size
  4. Creation Time
  5. Modification Time
  6. MFT Change Time
  7. Access Time

B-tree structures are employed within the special files of NTFS. Consequently, deleting an entry from the $I30 File translates to a logical removal. This means that when a file is deleted or hidden, its entry in the $I30 File may still be present in the slack space — an aspect of utmost significance in forensic analysis.

The Forensic Role of the $I30 File

The $I30 File stands as a vital forensic artifact, serving as an index that catalogues all file names and directories within an NTFS volume. Forensic analysts heavily rely on this index to reconstruct the file system and retrieve data from compromised systems.

Identification of Deleted or Hidden Files:

The $I30 File plays a crucial role in identifying deleted or hidden files on an NTFS volume. As previously explained, deleted file entries can potentially be recovered from the slack space, thereby aiding forensic analysis in reconstructing the system’s history and identifying valuable evidence.

Establishing a Timeline of Events:

By holding the access and modification times of the files within its entries, the $I30 File enables the establishment of a comprehensive timeline detailing events that occurred within a specific directory and its associated files.

Integrity Checking:

Another significant feature of the $I30 File is its ability to verify the integrity of the file system. Inconsistencies between the entries in the $I30 File and other data sources indicate potential tampering by unauthorized actors.

Conclusion

In conclusion, the $I30 File plays a pivotal role as an information-rich resource for forensic analysts, empowering them to reconstruct events and actions within compromised systems. Its capabilities in identifying evidence, detecting tampering, and providing critical insights make it an indispensable component in forensic investigations.

References

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Shellmates Club

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