Computer forensic investigations usually follow the standard digital forensic process (acquisition, analysis and reporting).[4] Investigations are performed on static data (i.e. acquired images) rather than “live” systems. This is a change from early forensic practices which, due to a lack of specialist tools, saw investigations commonly carried out on live data.
Techniques
A number of techniques are used during computer forensics investigations.
Cross-drive analysis
A forensic technique that correlates information found on multiple hard drives. The process, which is still being researched, can be used for identifying social networks and for performing anomaly detection.[6][7]
Live analysis
The examination of computers from within the operating system using custom forensics or existing sysadmin tools to extract evidence. The practice is useful when dealing with Encrypting File Systems, for example, where the encryption keys may be collected and, in some instances, the logical hard drive volume may be imaged (known as a live acquisition) before the computer is shut down.[8]
Deleted files
A common technique used in computer forensics is the recovery of deleted files. Modern forensic software have their own tools for recovering or carving out deleted data.[9] Most operating systems and file systems do not always erase physical file data, allowing it to be reconstructed from the physical disk sectors. File carving involves searching for known file headers within the disk image and reconstructing deleted materials.
Volatile data
When seizing evidence, if the machine is still active, any information stored solely in RAM that is not recovered before powering down may be lost.[5] One application of “live analysis” is to recover RAM data (for example, using Microsoft’s COFEE tool) prior to removing an exhibit.
RAM can be analyzed for prior content after power loss, because the electrical charge stored in the memory cells takes time to dissipate. The length of time for which data recovery is possible is increased by low temperatures and higher cell voltages. Holding unpowered RAM below −60 °C will help preserve the residual data by an order of magnitude, thus improving the chances of successful recovery. However, it can be impractical to do this during a field examination.[10]
Analysis tools
See also: list of digital forensics tools
A number of open source and commercial tools exist for computer forensics investigation. Typical forensic analysis includes a manual review of material on the media, reviewing the Windows registry for suspect information, discovering and cracking passwords, keyword searches for topics related to the crime, and extracting e-mail and pictures for review.[4]
referenced from Computer Forensic Article http://creativecommons.org/licenses/by-sa/3.0/
