Beginner’s Guide to Computer Forensics



Computer forensics is the practice of accumulating, analysing, and reporting on virtual records in a manner that is legally admissible. It can be used in the detection and prevention of crime and in any dispute wherein evidence is stored digitally. Computer forensics has similar examination degrees to different forensic disciplines and faces similar troubles.


About this guide

This guide discusses laptop forensics from an impartial perspective. It is not linked to specific legislation or meant to sell a particular employer or product and isn’t always written in bias of both law enforcement or business laptop forensics. It is aimed toward a non-technical target audience and provides a high-degree view of pc forensics. This guide makes use of the term “laptop”. However the ideas observe to any device capable of storing virtual information. Where methodologies were cited they’re provided as examples best and do no longer represent pointers or advice. Copying and publishing the whole or part of this text is certified totally under the phrases of the Creative Commons – Attribution Non-Commercial three.0 license.

Uses of computer forensics

There are few areas of crime or dispute where laptop forensics cannot be carried out. Law enforcement companies have been a number of the earliest and heaviest users of laptop forensics and consequently have regularly been at the leading edge of tendencies in the field. Computers may additionally represent a ‘scene of against the law’, for example with hacking [ 1] or denial of service assaults [2] or they’ll preserve evidence in the form of emails, internet history, documents or different files applicable to crimes which include homicide, kidnap, fraud and drug trafficking. It isn’t simply the content of emails, files and other files which can be of interest to investigators however also the ‘meta-data’ [3] associated with those documents. A computer forensic examination may reveal while a document first regarded on a computer, while it become final edited, whilst it was remaining stored or printed and which user achieved those actions. More currently, commercial organisations have used PC forensics to their benefit in a selection of instances which includes;

  • Intellectual Property robbery
  • Industrial espionage
  • Employment disputes
  • Fraud investigations
  • Forgeries
  • Matrimonial troubles
  • Bankruptcy Investigations
  • Inappropriate email and net use in the work area
  • Regulatory compliance


For evidence to be admissible it should be reliable and not prejudicial, meaning that in any respect degrees of this system admissibility have to be at the vanguard of a computer forensic examiner’s mind. One set of hints which has been broadly widespread to assist in that is the Association of Chief Police Officers Good Practice Guide for Computer Based Electronic Evidence or ACPO Guide for short. Although the ACPO Guide is aimed at United Kingdom law enforcement its most important concepts are relevant to all pc forensics in some thing legislature. The four essential principles from this manual have been reproduced beneath (with references to law enforcement removed): No motion should change records hung on a computer or garage media which can be ultimately relied upon in court.

In situations wherein a person reveals it necessary to access unique information held on a computer or garage media, that individual should be capable of doing so and be able to provide proof explaining the relevance and the consequences of their moves. An audit path or different document of all approaches implemented to laptop-based electronic evidence must be created and preserved. An impartial 0.33-celebration should be capable of examine those techniques and gain the identical end result. The man or woman in the price of the investigation has the usual obligation for ensuring that the law and these principles are adhered to. In summary, no changes have to be made to the authentic, however, if access/modifications are essential the examiner ought to recognize what they are doing and to file their moves.

Live acquisition

Principle 2 above may additionally raise the question: In what situation could changes to a suspect’s PC by using a PC forensic examiner be necessary? Traditionally, the PC forensic examiner might make a duplicate (or accumulate) information from a tool which is grew to become off. A write-blocker[4] could be used to make an specific bit for bit replica [5] of the original storage medium. The examiner might work then from this reproduction, leaving the unique demonstrably unchanged.

However, now and again it isn’t possible or ideal to exchange a computer off. It might not be possible to switch a computer off if doing so might result in enormous financial or other loss for the owner. It may not be suitable to switch a computer off if doing so would imply that probably treasured evidence can be misplaced. In each these occasions the computer forensic examiner might need to perform a ‘live acquisition’ which would involve running a small program on the suspect laptop in an effort to copy (or gather) the records to the examiner’s difficult drive.

By jogging such a software and attaching a destination pressure to the suspect laptop, the examiner will make adjustments and/or additions to the country of the computer which had been no longer present before his actions. Such moves could continue to be admissible as long as the examiner recorded their movements, become aware of their impact and turned into capable of explain their actions.

Stages of an examination

For the purposes of this newsletter the computer forensic examination process has been divided into six stages. Although they’re offered of their typical chronological order, it’s miles necessary in the course of an examination to be flexible. For example, during the evaluation level the examiner might also find a new lead which would warrant similarly computer systems being tested and could mean a go back to the evaluation degree.


Forensic readiness is an critical and on occasion omitted level within the exam system. In business pc forensics it may consist of educating clients approximately device preparedness; as an instance, forensic examinations will provide more potent evidence if a server or laptop’s integrated auditing and logging structures are all switched on. For examiners there are many areas in which prior organization can assist, together with education, regular testing and verification of software program and device, familiarity with rules, coping with sudden issues (e.G., what to do if infant pornography is present in the course of a commercial process) and ensuring that your on-website online acquisition kit is complete and in working order.


The evaluation level consists of the receiving of clear instructions, danger analysis and allocation of roles and assets. Risk evaluation for regulation enforcement may additionally encompass an evaluation at the probability of bodily danger on coming into a suspect’s assets and the way fine to cope with it. Commercial establishments additionally need to be privy to fitness and safety problems, while their assessment might also cover reputational and economic risks on accepting a specific venture.


The major part of the collection level, acquisition, has been introduced above. If acquisition is to be achieved on-website online in preference to in a PC forensic laboratory then this stage could encompass identifying, securing and documenting the scene. Interviews or conferences with personnel who can also maintain statistics which could be applicable to the exam (that could encompass the end customers of the laptop, and the supervisor and character chargeable for providing computer services) would usually be carried out at this level. The ‘bagging and tagging’ audit trail could begin right here by way of sealing any substances in particular tamper-evident bags. Consideration also needs to accept to securely and correctly transporting the material to the examiner’s laboratory.


Analysis relies upon on the specifics of each task. The examiner normally offers remarks to the purchaser in the course of analysis and from this dialogue the analysis might also take a one-of-a-kind direction or be narrowed to unique areas. Analysis must be correct, thorough, impartial, recorded, repeatable and finished within the time-scales available and sources allotted. There are myriad equipment available for computer forensics analysis. It is our opinion that the examiner should use any tool they sense comfy with so long as they are able to justify their choice. The fundamental requirements of a computer forensic tool is that it does what it is supposed to do and the simplest manner for examiners to be sure of that is for them to often test and calibrate the tools they use before evaluation takes region. Dual-tool verification can verify result integrity at some point of evaluation (if with tool ‘A’ the examiner finds artefact ‘X’ at region ‘Y’, then tool ‘B’ should replicate these effects.)


This degree generally includes the examiner generating a based report on their findings, addressing the factors within the initial instructions together with any next commands. It would additionally cover every other facts which the examiner deems applicable to the research. The document must be written with the quit reader in thoughts; in many instances the reader of the record could be non-technical, so the terminology must well known this. The examiner should also be organized to take part in meetings or cellphone conferences to talk about and complicated at the report.


Along with the readiness stage, the evaluate stage is often overlooked or ignored. This may be because of the perceived prices of doing work that is not billable, or the want ‘to get on with the next job’. However, a review degree incorporated into each exam can help keep money and lift the extent of exceptional by way of making destiny examinations more green and time effective. A assessment of an exam may be easy, quick and can begin during any of the above stages. It may additionally consist of a primary ‘what went incorrect and the way can this be progressed’ and a ‘what went nicely and how can it’s integrated into future examinations’. Feedback from the educating birthday celebration should also be sought. Any training learnt from this degree must be carried out to the next exam and fed into the readiness level.

Issues dealing with computer forensics

The issues going through computer forensics examiners may be broken down into 3 huge classes: technical, legal and administrative. Encryption – Encrypted documents or difficult drives may be not possible for investigators to view with out the perfect key or password. Examiners need to don’t forget that the important thing or password may be stored some place else at the computer or on every other computer which the suspect has had get right of entry to to. It may also are living within the unstable memory of a laptop (known as RAM [6] that’s typically misplaced on laptop shut-down; some other purpose to don’t forget the use of live acquisition strategies as mentioned above.

Increasing storage space – Storage media holds ever greater amounts of information which for the Examiner way that their analysis computer systems need to have sufficient processing power and available garage to successfully deal with looking and analysing enormous amounts of data.

New technology – Computing is an ever-converting vicinity, with new hardware, software and running structures being continuously produced. No single laptop forensic examiner can be an expert in all areas, though they may regularly be expected to analyse some thing which they have not dealt with before. In order to cope with this case, the examiner should be prepared and able to test and experiment with the behaviour of recent technology. Networking and sharing expertise with other pc forensic examiners is likewise very useful in this respect as it’s probably someone else may additionally have already encountered the same trouble.

Anti-forensics – Anti-forensics is the exercise of trying to thwart computer forensic analysis. This can also consist of encryption, the over-writing of data to make it unrecoverable, the amendment of documents’ meta-data and record obfuscation (disguising documents). As with encryption above, the evidence that such techniques were used may be saved some other place on the computer or on any other PC which the suspect has had access to. In our experience, it’s miles very uncommon to peer anti-forensics tools used efficiently and frequently enough to absolutely obscure both their presence or the presence of the evidence they had been used to cover.

Legal issues

Legal arguments may also confuse or distract from a computer examiner’s findings. An example here will be the ‘Trojan Defence’. A Trojan is a bit of computer code disguised as something benign however which has a hidden and malicious reason. Trojans have many makes use of, and include key-logging [7], uploading and downloading of documents and installation of viruses. A legal professional may be able to argue that actions on a computer have been no longer executed by using a user but had been automatic via a Trojan with out the consumer’s information; such a Trojan Defence has been efficiently used even if no trace of a Trojan or other malicious code was determined on the suspect’s laptop. In such instances, a capable opposing attorney, furnished with evidence from a ready laptop forensic analyst, have to be capable of brush aside such an argument.

Accepted standards – There are a plethora of requirements and recommendations in computer forensics, few of which appear like universally well-known. This is due to some of the motives inclusive of trendy-setting bodies being tied to precise law, requirements being aimed either at regulation enforcement or commercial forensics however no longer at each, the authors of such requirements not being customary with the aid of their friends, or high becoming a member of fees dissuading practitioners from taking part. Fitness to practice – In many jurisdictions there’s no qualifying body to test the competence and integrity of PC forensics experts. In such instances anybody may also present themselves as a laptop forensic expert, which may bring about laptop forensic examinations of questionable satisfactory and a poor view of the profession as a whole.

Resources and further studying

There does no longer seem like a exceptional quantity of cloth masking laptop forensics that is aimed at a non-technical readership. However the subsequent links at hyperlinks at the lowest of this page may also show to be of hobby show to be of interest:


1. Hacking: modifying a computer in manner which become not initially supposed so that you can benefit the hacker’s dreams.

2. Denial of Service assault: an try to prevent legitimate customers of a PC device from gaining access to that gadget’s information or offerings.

3. Meta-information: at a simple stage meta-information is records approximately records. It may be embedded within documents or saved externally in a separate document and can include facts about the document’s creator, format, introduction date and so on.

4. Write blocker: a hardware device or software which prevents any records from being modified or delivered to the garage medium being examined.

5. Bit reproduction: bit is a contraction of the time period ‘binary digit’ and is the fundamental unit of computing. A bit replica refers to a sequential copy of each bit on a storage medium, which incorporates regions of the medium ‘invisible’ to the user.

6. RAM: Random Access Memory. RAM is a laptop’s transient workspace and is volatile, which means that its contents are lost while the PC is powered off.

7. Key-logging: the recording of keyboard input giving the potential to read a consumer’s typed passwords, emails and different private records.

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