Computer forensics

Computer forensics is often confused with cybersecurity. Cybersecurity is about prevention and protection, while computer forensics is more reactionary and active, involving activities such as tracking and exposing. System security usually encompasses two teams, cybersecurity and computer forensics, which work together. A cybersecurity team creates systems and programs to protect data; if these fail, then the computer forensics team recovers the data and performs the investigation into the intrusion and theft. Both areas require knowledge of computer science.[7]

Computer forensics are used to convict those involved in physical and digital crimes. Some of these computer-related crimes include interruption, interception, copyright infringement, and fabrication. Interruption relates to the destruction and stealing of computer parts and digital files. Interception is the unauthorized access of files and information stored on technological devices.[8] Copyright Infringement is using, reproducing, and distributing copyrighted information, including software piracy. Fabrication is accusing someone of using false data and information put in the system through an unauthorized source. Examples of interceptions are the Bank NSP case, Sony.Sambandh.com case, and business email compromise scams. [9]

The computer forensic lab is a safe and protected zone where electronic data can be managed, preserved, and accessed in a controlled environment. There, there is a very much reduced risk of damage or modification to the evidence. Computer forensic examiners have the resources needed to elicit meaningful data from the devices that they are examining.[15]

A number of techniques are used during computer forensics investigations, and these include the following:

Cross-drive analysis

This is a forensic technique that correlates information found on multiple hard drives, and has been used to identify social networks and perform anomaly detection.[16][17] [18]

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.

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.[19] Most operating systems and file systems do not always erase physical file data, allowing investigators to reconstruct it from the physical disk sectors. File carving involves searching for known file headers within the disk image and reconstructing deleted materials.

Stochastic forensics

A method which uses stochastic properties of the computer system to investigate activities lacking digital artifacts. Its chief use is to investigate data theft.

Steganography

One of the techniques used to hide data is via steganography, the process of hiding data inside of a picture or digital image. An example would be to hide pornographic images of children or other information that a given criminal does not want to have discovered. Computer forensics professionals can fight this by looking at the hash of the file and comparing it to the original image (if available.) While the images appear identical upon visual inspection, the hash changes as the data changes.[20]

Phone Logs: Phone companies usually keep logs of calls received, which can be helpful when creating timelines and gathering the locations of persons when the crime occurred.[21]

Contacts: Contact lists help narrow down the suspect pool due to their connections with the victim or suspect.[21]

Text messages: Messages contain timestamps and remain in company servers indefinitely, even if deleted on the original device. Because of this, messages act as crucial records of communication that can be used to convict suspects.[21]

Photos: Photos can be critical in either supporting or disproving alibis by displaying a location or scene along with a timestamp of when the photo was taken.[21]

Audio Recordings: Some victims might have been able to record pivotal moments of the struggle, like the voice of their attacker or extensive context of the situation.[21]

Volatile data is any data that is stored in memory, or exists in transit, that will be lost when the computer loses power or is turned off. Volatile data resides in registries, cache, and random access memory (RAM). The investigation of this volatile data is called “live forensics”.

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.[14] 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.[22]

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.[23]

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.[11] Autopsy (software), Belkasoft Evidence Center, COFEE, EnCase are the some of tools used in Digital forensics.

A digital forensics analyst is responsible for preserving digital evidence, cataloging collected evidence, analyzing evidence in a manner relevant to the ongoing case, responding to cyber breaches (usually in a corporate context), writing reports containing findings, and testifying in court.[24] A digital forensic analyst may alternatively be referred to as a computer forensic analyst, digital forensic examiner, cyber forensic analyst, forensic technician, or other similarly named titles, although these roles perform the same duties. [25]

• IEEE Transactions on Information Forensics and Security
• Journal of Digital Forensics, Security and Law
• International Journal of Digital Crime and Forensics
• Journal of Digital Investigation
• International Journal of Digital Evidence
• International Journal of Forensic Computer Science
• Journal of Digital Forensic Practice
• Cryptologia
• Small Scale Digital Device Forensic Journal