Documentation of forensic processing methodologies and findings is critical. Without proper documentation, a forensic specialist has difficulty presenting findings. When security or audit findings become the object of a lawsuit or a criminal investigation, the legal system requires proper documentation. Without documentation, courts are unlikely to accept investigative results. Thus, a system forensics specialist must know the ins and outs of computer evidence processing methodology. This methodology includes strong evidence-processing documentation and good chain-of-custody procedures.
A system forensics specialist should have a good understanding of how computer hard disks and compact discs (CDs) are structured. A specialist should also know how to find data hidden in obscure places on CDs and hard disk drives.
A system forensics specialist should understand techniques and automated tools used to capture and evaluate file slack. A hard disk or CD is segmented into clusters of a particular size. Each cluster can hold only a single file or part of a single file. If you write a 1-kilobyte (KB) file to a disk that has a cluster size of 4 KB, the last 3 KB of the cluster are wasted. This unused space between the logical end of file and the physical end of file is known as file slack or slack space.
Most computer users have no idea that they’re creating slack space as they use a computer. In addition, pieces of a file may remain even after you delete it. This residual information in file slack is not necessarily overwritten when you create a new file. File slack is therefore a source of potential security leaks involving passwords, network logons, email, database entries, images, and word processing documents. A forensic specialist should know how to search file slack, identify what is and is not useful information, and document any findings.