Computer Forensic

 

Computer forensics is the application of investigation and analysis techniques to gather and preserve evidence from a particular computing device in a way that is suitable for presentation in a court of law. The goal of computer forensics is to perform a structured investigation and maintain a documented chain of evidence to find out exactly what happened on a computing device and who was responsible for it.

Computer forensics -- which is sometimes referred to as computer forensic science -- essentially is data recovery with legal compliance guidelines to make the information admissible in legal proceedings. The terms digital forensics and cyber forensics are often used as synonyms for computer forensics.

Digital forensics starts with the collection of information in a way that maintains its integrity. Investigators then analyze the data or system to determine if it was changed, how it was changed and who made the changes. The use of computer forensics isn't always tied to a crime. The forensic process is also used as part of data recovery processes to gather data from a crashed server, failed drive, reformatted operating system (OS) or other situation where a system has unexpectedly stopped working.

Why is computer forensics important?

In the civil and criminal justice system, computer forensics helps ensure the integrity of digital evidence presented in court cases. As computers and other data-collecting devices are used more frequently in every aspect of life, digital evidence -- and the forensic process used to collect, preserve and investigate it -- has become more important in solving crimes and other legal issues.

The average person never sees much of the information modern devices collect. For instance, the computers in cars continually collect information on when a driver brakes, shifts and changes speed without the driver being aware. However, this information can prove critical in solving a legal matter or a crime, and computer forensics often plays a role in identifying and preserving that information.

Digital evidence isn't just useful in solving digital-world crimes, such as data theft, network breaches and illicit online transactions. It's also used to solve physical-world crimes, such as burglary, assault, hit-and-run accidents and murder.

Businesses often use a multilayered data management, data governance and network security strategy to keep proprietary information secure. Having data that's well managed and safe can help streamline the forensic process should that data ever come under investigation.

Businesses also use computer forensics to track information related to a system or network compromise, which can be used to identify and prosecute cyber attackers. Businesses can also use digital forensic experts and processes to help them with data recovery in the event of a system or network failure caused by a natural or other disaster.

Types of computer forensics

There are various types of computer forensic examinations. Each deals with a specific aspect of information technology. Some of the main types include the following:

Database forensics. The examination of information contained in databases, both data and related metadata.

Email forensics. The recovery and analysis of emails and other information contained in email platforms, such as schedules and contacts.

Malware forensics. Sifting through code to identify possible malicious programs and analyzing their payload. Such programs may include Trojan horses, ransomware or various viruses.

Memory forensics. Collecting information stored in a computer's random access memory (RAM) and cache.

Mobile forensics. The examination of mobile devices to retrieve and analyze the information they contain, including contacts, incoming and outgoing text messages, pictures and video files.

Network forensics. Looking for evidence by monitoring network traffic, using tools such as a firewall or intrusion detection system.

How does computer forensics work?

Forensic investigators typically follow standard procedures, which vary depending on the context of the forensic investigation, the device being investigated or the information investigators are looking for. In general, these procedures include the following three steps:

Data collection. Electronically stored information must be collected in a way that maintains its integrity. This often involves physically isolating the device under investigation to ensure it cannot be accidentally contaminated or tampered with. Examiners make a digital copy, also called a forensic image, of the device's storage media, and then they lock the original device in a safe or other secure facility to maintain its pristine condition. The investigation is conducted on the digital copy. In other cases, publicly available information may be used for forensic purposes, such as Facebook posts or public Venmo charges for purchasing illegal products or services displayed on the Vicemo website.

Analysis. Investigators analyze digital copies of storage media in a sterile environment to gather the information for a case. Various tools are used to assist in this process, including Basis Technology's Autopsy for hard drive investigations and the Wireshark network protocol analyzer. A mouse jiggler is useful when examining a computer to keep it from falling asleep and losing volatile memory data that is lost when the computer goes to sleep or loses power.

Presentation. The forensic investigators present their findings in a legal proceeding, where a judge or jury uses them to help determine the result of a lawsuit. In a data recovery situation, forensic investigators present what they were able to recover from a compromised system.

Techniques forensic investigators use

Investigators use a variety of techniques and proprietary forensic applications to examine the copy they've made of a compromised device. They search hidden folders and unallocated disk space for copies of deleted, encrypted or damaged files. Any evidence found on the digital copy is carefully documented in a finding report and verified with the original device in preparation for legal proceedings that involve discovery, depositions or actual litigation.

Computer forensic investigations use a combination of techniques and expert knowledge. Some common techniques include the following:

Reverse steganography. Steganography is a common tactic used to hide data inside any type of digital file, message or data stream. Computer forensic experts reverse a steganography attempt by analyzing the data hashing that the file in question contains. If a cybercriminal hides important information inside an image or other digital file, it may look the same before and after to the untrained eye, but the underlying hash or string of data that represents the image will change.

Stochastic forensics. Here, investigators analyze and reconstruct digital activity without the use of digital artifacts. Artifacts are unintended alterations of data that occur from digital processes. Artifacts include clues related to a digital crime, such as changes to file attributes during data theft. Stochastic forensics is frequently used in data breach investigations where the attacker is thought to be an insider, who might not leave behind digital artifacts.

Cross-drive analysis. This technique correlates and cross-references information found on multiple computer drives to search for, analyze and preserve information relevant to an investigation. Events that raise suspicion are compared with information on other drives to look for similarities and provide context. This is also known as anomaly detection.

Live analysis. With this technique, a computer is analyzed from within the OS while the computer or device is running, using system tools on the computer. The analysis looks at volatile data, which is often stored in cache or RAM. Many tools used to extract volatile data require the computer in to be in a forensic lab to maintain the legitimacy of a chain of evidence.

Deleted file recovery. This technique involves searching a computer system and memory for fragments of files that were partially deleted in one place but leave traces elsewhere on the machine. This is sometimes known as file carving or data carving.