The purpose of this research paper is to research information on open source digital forensic tools that are assess-able for free, usually online. To review types of digital forensic tools available and what they do. The basic definition of what open source and digital forensics is will be defined, and how Open Source Software (OSS) digital forensic tools can help accomplished data retrieval. The pros and cons of why OSS should be considering as a viable digital forensic tool-set is also covered.
Digital Forensics and Incident Response and Tools
Digital forensics and Incident Response (DFIR) is the method of investigating and analyzing data information for the purpose of presenting, an ordered report that shows a chain of evidence to find out what happened on a computer and who was responsible, to a court of law. SearchSecurity. (September 2004). DFIR is being more commonly used as more and more people use computers in their daily life, from smart phones, game stations, and laptops. DFIR can help convict anyone of any crime that involved a computer, wither it is prostitution, child pornography or a white collar crime like embezzlement.
DFIR Tools are the free and proprietary applications used by DFIR experts to retrieve the results to hand over to the legal system. They allow investigators the ability to examine the contents of the hard drive without making changes to the data held within. Information that is retrieved can come from deleted files, encrypted, or damaged files SearchSecurity. (September 2004).
Open Source Software
Open Source Software (OSS) is a set of practices used to collaborate with software source code that has been made freely available through copywriting laws. It is also commonly known as FOSS (Free Open Source Software), although most OSS is free, not all is but for this research paper I will be covering mostly the free version of OSS. Individuals separated can come from diverse cultural, corporate boundaries, language and other characteristics in order to work together to create complex, non-proprietary software. Software is open sourced when it is free to redistribute, the source code is redistributed with it as well as in compiled mode. The open source licensing was created to make the source code of a program readily available to anyone that requests it. By making the source code available for anyone, it helps in developing stable software because the whole community is able to create changes and redistribute their own version of the software. Open source software protects the original author of the software, does not discriminate in anyway on how it can be used, cannot be specific to a product or software, cannot restrict other software and has to be technology neutral (open source, n.d.). There are several variants of the open source licensing contract that can be reviewed at opensource.org (http://www.opensource.org/licenses/category).
Some of the more widely known open source licenses cover the GNU(Graphic environment of sever Linux desktops), Mozilla (Firefox, Thunderbird), MIT, BSD (like Unix), and Eclipse (Eclipse IDE). Because of the lack of dependency on software vendors, open source software allows the software to transform and morph into potentially anything the users and developers need the software to do. It gives users the freedom to use it when they want, how they want and on their own terms.
Why OSS DFIR Tools
Open Source digital forensic tools addresses specific gap in forensic capabilities of proprietary DFIR tools. The tools range for analyzing memory dumps, disks, network traces, cell phones, and memory images from game consoles. Besides the fact that some of the tools focus on one specific area of digital forensics of the incident response building, make them invaluable to some investigators who find the complete packaging of some DFIR proprietary tools cumbersome and lacking in some areas.
Financially, companies and governments are always looking for ways to cut budget costs that is the same for DFIR investigators trying to find work. An investigator using DFIR tools can offer a lower price to customers than a person that has to forward the expensive cost of proprietary tools to the customer. Even law enforcement that has an easier time justifying expenses to budget reports in other departments like traffic enforcement, and drug trafficking. Because of the high cost involved in proprietary applications, the follow up cost for updates may be neglected, leaving the software antiquated and not viable in future investigations.
Legally procedures for finding digital evidence need to be defended in court as being testable, published under peer review, show the possible error rate, and are marginally accepted in the relevant scientific community. Because proprietary tools are closed source and the companies offering the tools do not what to acknowledge mistakes in their software, it makes a case all by itself for choosing OSS digital forensic tools during investigation. OSS allows the source code to be evaluated, tested and error rates to be traced. OSS tools are also greatly accepted by the DFIR community (Carrier, 2002). As Brian Carrier, (Carrier, 2002) reported, “The digital forensic market should not be approached in the same way that other software markets are. The goal of a digital forensic tool should not be market domination by keeping procedural techniques secret.” While Carrier may be a little bias since he developed most of the code in Sleuth Kit, Autopsy, and mac-robber, his experience in digital forensic just proves the fact that it is important to keep OSS DGIR tools in mind.
Counterproductive to this paper, it is important to note that there usually is a larger learning curve when dealing with OSS DFIR tools since some run from command prompts and from Nix (Linux, Unix, BSD) operating systems. Also since they usually focus on one component of DFIR, it requires several different applications that need to be tied together to build a report. Because some of the tools take a lot of time to college and arrange data for a report it is sometimes better to use in a lab then in the field.
While open source digital forensic tools are abound, and you can take advantage of all of them while avoiding paying fees for commercial products, there are several good commercial tools that are available also. Because digital forensics is such a vast field of study, it is important to not rely on just one set of tools and to research and test other methods to discover and fight anti-forensics.
Good luck with any future digital forensic test cases you attempt, please make sure that it is done ethically and legally.
More information on OSS DFIR tools can be found at sites like IEEE, open source references at the National Institute of Technology (NIST), the National Software Reference Library (NSRL) form NIST, and government studies and college studies on OSS alternatives in DFIR. Additionally there is a growing amount of information from personal websites and OSS developers on DFIR that may be useful. I totally agree with Schneier (2010), that we, “would encorage everybody to download and learn the tools not just because they can do forensics but because most of them can also be used for other things such as finding things in memory and hard drives that should not be there which many AV tools cannot do and to help put systems back together again.”
Future Note: I plan to compare and contrast some of the more common tools that I will continue to study.References
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DFF (n.d.) Open Source Digital Investigation Framework. Retrieved 4/17/2012, from http://www.digital-forensic.org/
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LinuxLinks (n.d.) 6 of the Best Free Linux Digital Forensics Tools, retrieved 4/5/201. From http://www.linuxlinks.com/article/20110115103656314/DigitalForensics.html
Nikkel, B. (June 2012) Practical Computer Forensics using Open Source tools, retrieved 4/23/2012, from www.digitalforensics.ch/nikkel08.pdf
Open Source. (n.d.) The Open Source Definition. Open Source Initiative. Retrieved from http://www.opensource.org/docs/osd
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