Disk Serial Number

Disk Serial Number

DiskSerialNumber is a sandbox setting in Sandboxie Ini available since v1.15.2 / 5.70.2. This setting allows assigning custom serial numbers to specific disk devices within sandboxes, working in conjunction with Hide Disk Serial Number.

Syntax

DiskSerialNumber=<DeviceName>,<SerialNumber>
  • DeviceName: Windows device name (e.g., HarddiskVolume1, HarddiskVolume2)
  • SerialNumber: Custom serial number in hexadecimal format (with or without hyphens)

Example Usage

[DefaultBox]

HideDiskSerialNumber=y
DiskSerialNumber=HarddiskVolume1,1234-ABCD
DiskSerialNumber=HarddiskVolume2,5678-EFGH
DiskSerialNumber=HarddiskVolume3,9ABC-DEF0

Prerequisites

  • Requires HideDiskSerialNumber=y to be enabled in the same sandbox[^1].
  • Without this prerequisite, the DiskSerialNumber settings are ignored.

Serial Number Formats

Supported Formats

  • Hyphenated: 1234-ABCD, AA-BB-CC-DD.
  • Plain: 1234ABCD, AABBCCDD.
  • Mixed: Any combination of hex digits with optional hyphens.

Valid Examples

DiskSerialNumber=HarddiskVolume1,1234ABCD
DiskSerialNumber=HarddiskVolume2,12-34-AB-CD
DiskSerialNumber=HarddiskVolume3,12345678
DiskSerialNumber=HarddiskVolume4,DEADBEEF

Invalid Formats

  • Non-hexadecimal characters (G-Z).
  • Odd number of hex digits.
  • Empty strings.
  • Special characters other than hyphens.

Device Name Discovery

Method 1: Using WMIC Command

Run in Command Prompt to list available disk volumes:

wmic logicaldisk get caption,volumeserialnumber,deviceid

Method 2: Using Disk Management

  1. Open Disk Management (diskmgmt.msc).
  2. Right-click on volumes to see properties.
  3. Note the volume labels and drive letters.

Method 3: Registry Inspection

Check registry key: HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices

Method 4: Testing with Random Values

  1. Set test configurations:
DiskSerialNumber=HarddiskVolume1,11111111
DiskSerialNumber=HarddiskVolume2,22222222
DiskSerialNumber=HarddiskVolume3,33333333
  1. Run vol C:, vol D:, etc., in the sandbox to identify which device corresponds to which drive.

Technical Implementation

Device Path Resolution

  • Sandboxie extracts device names from Windows NT paths with \Device\ prefix[^2].
  • Device name parsing stops at the next backslash or string terminator[^3].
  • Failed device extraction results in random serial number generation[^4].

Hexadecimal Processing

  • Custom parser handles both hyphenated and plain hex formats[^5].
  • Invalid hex strings trigger fallback to random generation[^6].
  • Byte order is automatically swapped to match Windows DWORD format[^7].

Caching Mechanism

  • Serial numbers are cached per session for performance[^8]
  • Thread-safe implementation using critical sections[^9]
  • Cache keys are based on original hardware serial numbers[^10]

Use Cases

Application Testing

  • Test software behavior with specific disk serial number patterns.
  • Simulate different hardware configurations.
  • Debug serial number-dependent functionality.

Privacy Enhancement

  • Replace real hardware identifiers with known values.
  • Create consistent sandbox fingerprints.
  • Prevent hardware-based tracking.

Troubleshooting

Common Issues

Setting Not Applied

  • Ensure HideDiskSerialNumber=y is enabled.
  • Verify correct device name format.
  • Check hexadecimal string validity.

Wrong Device Targeted

  • Use device discovery methods to identify correct names.
  • Test with unique serial numbers to verify mapping.

Random Values Still Returned

  • Invalid hex format triggers random fallback.
  • Device name mismatch results in random generation.
  • Missing HideDiskSerialNumber prerequisite.

Related Settings

Configuration Availability

  • INI Configuration: Available
  • Plus UI: Not available (INI-only setting)
  • Classic UI: Not available

[^1]: Prerequisite Check: The HideDiskSerialNumber setting must be enabled for device-specific serial number mapping to function (kernel.c).

[^2]: Device Path Parsing: Sandboxie searches for \Device\ prefix in NT path strings to extract device names (kernel.c).

[^3]: Name Extraction Logic: Device name parsing terminates at the first backslash or null character after the \Device\ prefix (kernel.c).

[^4]: Fallback Behavior: Empty device names trigger Dll_rand() for random serial number generation (kernel.c).

[^5]: Hex Parser Implementation: hex_string_to_uint8_array() function processes hex strings while skipping hyphen characters (custom.c).

[^6]: Error Handling: Invalid hex characters, odd digit counts, or parsing failures return FALSE, triggering random generation (custom.c).

[^7]: Endianness Conversion: Byte swapping is performed when swap_bytes=TRUE to match Windows little-endian DWORD format (custom.c).

[^8]: Session Persistence: map_insert() stores computed serial numbers using original hardware values as keys (kernel.c).

[^9]: Thread Safety: Critical section Kernel_DiskSN_CritSec protects concurrent access to the serial number cache (kernel.c5).

[^10]: Cache Key Strategy: Original disk serial numbers serve as map keys for consistent per-session value retrieval (kernel.c).