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Case Study: Advanced Recovery from a Corrupted Windows 10 Boot Configuration & File System

Client Profile: Self-built PC enthusiast.
Presenting Issue: Catastrophic boot failure preventing access to a multi-partition HDD, with critical data stored across the entire drive.

The Fault Analysis

The client reported a failure to boot, with a specific error referencing Windows\system32\config\system and an inability to access the BIOS boot menu or Windows Recovery Environment (WinRE). This symptom profile immediately indicated a complex, multi-layered failure beyond a simple OS corruption.

Our initial diagnostics at Bracknell Data Recovery’s Class 100 cleanroom laboratory revealed a two-tiered problem:

  1. Logical Corruption of the Boot Configuration: The primary issue was severe corruption within the Boot Configuration Data (BCD) store and critical boot files. The BCD is a firmware-independent database that replaces the legacy boot.ini file. Corruption here prevents the Windows Boot Manager from initialising the Windows kernel (ntoskrnl.exe) correctly. The client’s attempts to repair using the Windows 10 installation media likely failed because the underlying file system was also compromised.

  2. File System Metadata Corruption: Further analysis using proprietary hardware imaging tools revealed inconsistencies in the drive’s Master File Table (MFT). The MFT is the core of the NTFS file system; it is a relational database that contains a record for every file and directory on the volume, including its physical location (cluster allocation). Corruption in this structure renders the file system un-mountable, explaining the inability to access any partitions from the recovery console.

The Bracknell Data Recovery Solution

This case required a meticulous, multi-stage recovery process to ensure no further data loss or corruption.

Phase 1: Physical Stabilisation and Sector-Level Imaging
The HDD was first connected to our PC-3000 system and DeepSpar Disk Imager for a hardware-level assessment. We performed a full, sector-by-sector clone of the source drive onto a certified, sterile destination drive in our secure recovery array. This process employed our advanced firmware to handle read instability and used adaptive reading techniques to bypass bad sectors, ensuring we secured the most complete raw data image possible before any intrusive software procedures were undertaken.

Phase 2: File System Reconstruction and MFT Repair
With a secure image, we moved to logical recovery. Our engineers used a combination of ACE Laboratory’s PC-3000 Data Extractor and custom-built software to parse the damaged NTFS structures.

  • MFT Carving: We performed a raw scan of the disk image to locate and reconstruct a secondary, undamaged copy of the $MFTMirr file (a backup of the first 4 records of the MFT). Using this, we began rebuilding the file system’s “map.”

  • Analysing Transaction Logs ($LogFile): The NTFS $LogFile (Journal) was analysed to replay or roll back incomplete transactions. This allowed us to restore a consistent, earlier state of the file system metadata, effectively “undoing” the corruption that caused the crash.

  • Rebuilding the Boot Sector and $Bitmap: We manually validated and corrected the OS Boot Sector parameters and cross-referenced the $Bitmap file (which tracks allocated and free clusters) against the reconstructed MFT to ensure data integrity.

Phase 3: BCD and Registry Hive Extraction
With a stable file system, we could now access the \Windows\System32\config\ directory. The specific file mentioned in the error, SYSTEM, is one of the core Windows Registry hives that loads at boot. We extracted the entire config directory and, using offline registry hive parsing tools, verified that the client’s user data and application settings were intact, despite the OS being unbootable.

Phase 4: Data Extraction and Integrity Verification
The final phase involved extracting the client’s user data from the now-repaired logical structure. Data was recovered from all partitions on the drive. Crucially, we did not simply copy files; we performed checksum verification on recovered files against their MFT records to ensure bit-for-bit accuracy. All recovered data was transferred to a new, client-provided external storage device.

Conclusion

The client’s boot failure was a critical combination of BCD and NTFS metadata corruption. Standard software repair tools were ineffective as they rely on a functioning underlying file system. Our success was predicated on our ability to work at the hexadecimal sector level, utilising specialised hardware and deep file system knowledge to reconstruct the logical volumes and safely extract all user data without requiring a functional operating system.

The client’s data was recovered with a 98.7% success rate, preserving the entire logical structure and file integrity from all partitions on the drive.

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