What is computer forensics?
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.
As the world becomes more reliant on digital technology for the core functions of life, cybercrime is rising. As such, computer forensic specialists no longer have a monopoly on the field. See how the police in the U.K. are adopting computer forensic techniques to keep up with increasing rates of cybercrime.
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.
Often, multiple tools are used in computer forensic investigations to validate the results they produce. Learn how a researcher at Kaspersky Lab in Asia created an open source forensics tool for remotely collecting malware evidence without compromising system integrity.
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.
Find out more about computer forensic analytics in this chapter from the book Python Forensics: A Workbench for Inventing and Sharing Digital Forensic Technology, by Chet Hosmer. It shows how to use Python and cybersecurity technology to preserve digital evidence.
How is computer forensics used as evidence?
Computer forensics has been used as evidence by law enforcement agencies and in criminal and civil law since the 1980s. Some notable cases include the following:
- Apple trade secret theft. An engineer named Xiaolang Zhang at Apple's autonomous car division announced his retirement and said he would be moving back to China to take care of his elderly mother. He told his manager he planned to work at an electronic car manufacturer in China, raising suspicion. According to a Federal Bureau of Investigation (FBI) affidavit, Apple's security team reviewed Zhang's activity on the company network and found, in the days prior to his resignation, he downloaded trade secrets from confidential company databases to which he had access. He was indicted by the FBI in 2018.
- Enron. In one of the most commonly cited accounting fraud scandals, Enron, a U.S. energy, commodities and services company, falsely reported billions of dollars in revenue before going bankrupt in 2001, causing financial harm to many employees and other people who had invested in the company. Computer forensic analysts examined terabytes of data to understand the complex fraud scheme. The scandal was a significant factor in the passing of the Sarbanes-Oxley Act of 2002, which set new accounting compliance requirements for public companies. The company declared bankruptcy in 2001.
- Google trade secret theft. Anthony Scott Levandowski, a former executive of both Uber and Google, was charged with 33 counts of trade secret theft in 2019. From 2009 to 2016, Levandowski worked in Google's self-driving car program, where he downloaded thousands of files related to the program from a password-protected corporate server. He departed from Google and created Otto, a self-driving truck company, which Uber bought in 2016, according to The New York Times. Levandowski plead guilty to one count of trade secrets theft and was sentenced to 18 months in prison and $851,499 in fines and restitution. Levandowski received a presidential pardon in January 2021.
- Larry Thomas. Thomas shot and killed Rito Llamas-Juarez in 2016 Thomas was later convicted with the help of hundreds of Facebook posts he made under the fake name of Slaughtaboi Larro. One of the posts included a picture of him wearing a bracelet that was found at the crime scene.
- Michael Jackson. Investigators used metadata and medical documents from Michael Jackson's doctor's iPhone that showed the doctor, Conrad Murray, prescribed lethal amounts of medication to Jackson, who died in 2009.
- Mikayla Munn. Munn drowned her newborn baby in the bathtub of her Manchester University dorm room in 2016. Investigators found Google searches on her computer containing the phrase "at home abortion," which were used to convict her.
Murder is just one of the many types of crime computer forensics can aid in combating. Learn how forensic financial analysis software is used to combat fraud.
Computer forensics careers and certifications
Computer forensics has become its own area of scientific expertise, with accompanying coursework and certification. The average annual salary for an entry-level computer forensic analyst is about $65,000, according to Salary.com. Some examples of cyber forensic career paths include the following:
- Forensic engineer. These professionals deal with the collection stage of the computer forensic process, gathering data and preparing it for analysis. They help determine how a device failed.
- Forensic accountant. This position deals with crimes involving money laundering and other transactions made to cover up illegal activity.
- Cybersecurity analyst. This position deals with analyzing data once it has been collected and drawing insights that can later be used to improve an organization's cybersecurity strategy.
A bachelor's degree -- and, sometimes, a master's degree -- in computer science, cybersecurity or a related field are required of computer forensic professionals. There are several certifications available in this field, including the following:
- CyberSecurity Institute's CyberSecurity Forensic Analyst. This credential is designed for security professionals with at least two years of experience. Testing scenarios are based on actual cases.
- International Association of Computer Investigative Specialists' Certified Forensic Computer Examiner. This program focuses primarily on validating the skills necessary to ensure business follows established computer forensic guidelines.
- EC-Council's Computer Hacking Forensic Investigator. This certification assesses an applicant's ability to identify intruders and collect evidence that can be used in court. It covers search and seizure of information systems, working with digital proof and other cyber forensics skills.
- International Society of Forensic Computer Examiners' (ISFCE) Certified Computer Examiner. This forensic examiner program requires training at an authorized bootcamp training center, and applicants must sign the ISFCE Code of Ethics and Professional Responsibility.
Learn more about a cyber forensics career from this interview with Amanda Rousseau, senior malware researcher at Endgame (now at Facebook), who began her career performing computer forensic investigations at the Department of Defense Cyber Crime Center.