The Process for Recovering Electronic Evidence


There are two primary steps in the process of recovering electronic data; “acquisition” of the target medium, and a forensic byte-by-byte analysis of the data.

Computer forensic science was created to address the specific and articulated needs of law enforcement to make the most of this new form of electronic evidence. Computer forensic science is the science of acquiring, preserving, retrieving, and presenting data that has been processed electronically and stored on computer medium.

Rather than producing interpretative conclusions, as in many forensic disciplines, computer forensic science produces direct information and data that may have some significance in a case. This type of direct data collection has wide-ranging implications for both the relationship between the investigator and the forensic scientist and the work product of the forensic computer examination.

Using customized computer forensic tools, the target medium is acquired through a non-invasive complete area-by-area bit-stream image procedure. During the imaging process, it is critical the mirror image be acquired in a DOS environment. Switching on the computer and booting into its operating system will subtly modify the file system, potentially destroying some recoverable evidence.

The resulting image becomes the “evidence file,” which is mounted as a read-only or “virtual” file, on which the forensic examiner will perform their analysis. The forensics software used by CFI creates an evidence file that will be continually verified by a Cyclical Redundancy Checksum (“CRC”) algorithm for every 64 sectors (block) of data and a by a MD5 128 bit encryption hash file for the entire image. Both steps verify the integrity of the evidence file, and confirms the image has remained unaltered and forensically intact. Using the MD5 hash encryption, changing even one bit of data will result in a notification that the evidence file data has been changed and is no longer forensically intact.

The Computer Fraud and Abuse Act (CFAA), 18 U.S.C. 1030, a federal criminal statute outlawing various computer crimes, provides a civil remedy for companies victimized by a violation of the statute.In this new digital age, the CFAA is fast becoming recognized as a proactive tool that can be used by companies to retrieve stolen data, prevent its dissemination in the marketplace and obtain compensatory damages resulting from its theft, use and malicious destruction.

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