Ensuring Evidence Integrity: Key Steps in Digital Forensic Acquisition

 Acquisition (Digital Forensics)

In digital forensics, "acquisition" refers to the critical initial step of collecting digital evidence from a suspect device, such as a computer or smartphone, by creating a forensically sound copy of its data. This ensures that the original device remains unaltered and the collected data can be used as legal evidence in court. This process involves using specialized tools to capture a complete bit-for-bit image of the device's storage media without modifying the original data on the device itself. 

Key aspects of acquisition in digital forensics:

• Preserving integrity: The primary goal of the acquisition is to create an exact copy of the digital evidence while ensuring its integrity, meaning no changes are made to the original data on the device during the acquisition process. 
• Write-blocking: To prevent accidental modification of the original data, digital forensics professionals use "write-blocking" devices or software that prevent the acquisition tool from writing any data back to the examined device. 
• Image creation: The acquired data is typically captured as a "forensic image," a bit-for-bit copy of the entire storage device, including allocated and unallocated space. This allows for a thorough analysis of all potential data remnants. 
• Hashing: A cryptographic hash (like MD5 or SHA-256) is calculated on the image file to verify the integrity of the acquired image. This hash acts as a unique fingerprint that can be compared later to ensure no data corruption occurs during acquisition. 

Types of Acquisition:

• Physical Acquisition: This involves creating a complete image of the entire storage device, capturing all data sectors, including deleted files and unallocated space. 
• Logical Acquisition: This method only extracts specific file types or data within the system hierarchy, like user files, emails, and application data. 
• Live Acquisition: This method captures a snapshot of a running system, including RAM memory, active processes, and network connections, which can be crucial for investigating volatile data. 

Important considerations during acquisition:

• Chain of Custody: Proper documentation of the acquisition process, including timestamps, device details, and who handled the evidence, is crucial to maintain the chain of custody and ensure legal admissibility. 
• Forensic Tools: Specialized digital forensics tools are used to perform acquisition, ensuring the process is conducted according to industry standards and legal requirements. 
• Data Validation: After acquisition, thorough image verification is necessary to confirm that the data is complete and accurate.

This is covered in Security+.