Computer Forensics Analysis (sometimes known as Computer Forensic Science) is a branch of digital forensic science pertaining to legal evidence found in computers and digital storage media. The goal of computer forensics is to examine digital media in a forensically sound manner with the aim of identifying, preserving, recovering, analyzing and presenting facts and opinions about the information.
Computer forensic investigations usually follow the standard digital forensic process (acquisition, analysis and reporting). Investigations are performed on static data (i.e. acquired images) rather than "live" systems. This is a change from early forensic practices where a lack of specialist tools led to investigators commonly working on live data.
A number of techniques are used during computer forensics investigations:
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. One application of "live analysis" is to recover RAM data (for example, using Microsoft's COFEE tool, windd, WindowsSCOPE) prior to removing an exhibit. CaptureGUARD Gateway bypasses Windows login for locked computers, allowing for the analysis and acquisition of physical memory on a locked computer.
RAM can be analyzed for prior content after power loss, because the electrical charge stored in the memory cells takes time to dissipate, an effect exploited by the cold boot attack. The length of time that data is recoverable is increased by low temperatures and higher cell voltages. Holding unpowered RAM below −60 °C helps preserve residual data by an order of magnitude, improving the chances of successful recovery. However, it can be impractical to do this during a field examination.
Some of the tools needed to extract volatile data, however, require that a computer be in a forensic lab, both to maintain a legitimate chain of evidence, and to facilitate work on the machine. If necessary, law enforcement applies techniques to move a live, running desktop computer. These include a mouse jiggler, which moves the mouse rapidly in small movements and prevents the computer from going to sleep accidentally. Usually, an uninterruptible power supply (UPS) provides power during transit.
However, one of the easiest ways to capture data is by actually saving the RAM data to disk. Various file systems that have journaling features such as NTFS and ReiserFS keep a large portion of the RAM data on the main storage media during operation, and these page files can be reassembled to reconstruct what was in RAM at that time.
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.