Collecting Internet Evidence, Part 1
Investigative procedures are different in Internet-based crimes than they are with attacks on a single network.
You have been attacked, information stolen, data modified. You may not even know these problems exist on your network, desktops, mobile devices, and data centers. You have dedicated resources to prevent these problems, but now that it has occurred, you need to collect information on the malicious behavior to prevent it from happening again, as well as to develop a case if you choose to pursue the perpetrators.
Todd Shipley and Art Bowker co-authored "Investigating Internet Crimes: An Introduction to Solving Crimes in Cyberspace," which was just released this December. I contacted Todd to interview him about collecting Internet evidence. This blog is part 1 of that interview.
I have heard of network forensics and Internet forensics. What is the difference?
Todd Shipley: First, you have to define the terms "network forensics" and "Internet forensics". Network forensics can broadly be defined as the identification, collection, and documentation of actions committed against an individual network. This can be a very large network, but what we are collecting and documenting are actions taken against that individual network (by internal or external sources) by those in control of the network [who gain] access to the hardware and software running on the network.
The term "Internet forensics" is most often applied by digital forensic examiners as the identification of Internet-related artifacts on a computer that has been forensically imaged and [is] again under the investigator's control.
Investigating crimes on the Internet is cases [in which] the investigator is looking at data live on the Internet and stored on computers and servers not under the investigator's direct control. The interaction with this data is done through one of several standard protocols and tools as simple as your favorite browser. However, this data is often in motion on these servers, meaning that data is added, subtracted, and deleted constantly, as demonstrated through most social media sites. The data the investigator finds relevant to his investigation may be changed, or not there at all, when they go back a second time to look at the data. Collecting and documenting their findings in real time are essential parts of the Internet investigator's function.
Is there any standardization of the investigation process?
TS: Investigating crimes on the Internet often depends on the crime. In law enforcement, the most thoroughly documented processes are among the Internet Crimes Against Children (ICAC) Task Forces nationwide. The investigators assigned to crimes against children are highly trained and supervised. The organization applies procedures for investigating these crimes across its membership.
With that as the example, most other Internet crimes investigated do not rise to this level of standardization. The National Institute of Justice (NIJ), part of the U.S. DOJ, published a text on Investigating Crime on the Internet. It was an early attempt at providing a general guidance for law enforcement investigators looking into Internet crimes. Since then a variety of books have touched on the topic, but most have focused on the forensic examination of individual computers or networks and not the data in movement on the Internet.
What are the questions and procedures for investigating Internet forensics?
TS: Understanding the environment they are going into is paramount. Build a plan for the investigation: Why are you investigating the case? Where are you looking on the Internet for victims, suspect, and witnesses? Does your agency or company have a policy regarding Internet investigations? What does the policy allow? Are you conducting an investigation from your office desktop or are you using a computer segregated from the agency/company network to prevent contamination of the entire network? What methods are they using to document their activities and any evidence they may find? What are the local, state and federal laws regarding these investigations and investigator's actions online? What is the current case law regarding its use and introduction into any litigation? How are you storing and maintaining case data from the investigation? Is the investigator going undercover on the Internet? If so, what is the agency/company policy governing the investigator during these operations? What training has the investigator had in conducting investigations on the Internet?
These are a few of the things that need to be answered long before the investigator goes on the Internet.
The items that stand out from the list above include:
1) [Establish] a policy governing the investigation of Internet crimes
2) Define a plan of the investigation before you go online
3) Use a computer that if compromised will not allow for further compromise of the agency or company network
4) Obtain training for the investigation of Internet-related crimes
5) Understand the changing legal landscape regarding the use of information found on the Internet.
Are there legal issues and limitations for performing Internet forensics?
TS: There are legal issues regarding the investigation of Internet crimes. Traditional investigative limitations apply, such as an undercover investigator's limitations regarding entrapment.
There are also traditional methods of investigation that are governed by internal policy and procedures that most often apply to Internet investigations but are often overlooked from a management point of view. The case law is developing rapidly surrounding the collection, preservation, and presentation of data found on the Internet. In most cases the data should be handled no differently than other objectively collected digital evidence found on a computer or cell phone. Collect it, apply a Hash algorithm to the collected data, and document what you have done.
Now the collection can be in very different forms, as the data cannot always be directly accessed. A snapshot of the browser on the screen may be the only documentation made of the evidence. Courts have been accepting the authentication of the snapshot as the representation of what the person collecting the data saw. However, there still is a validation issue as to whether or not the data is true or can be tied to the person(s) to have allegedly posted the data. The investigator still needs to use traditional methods of investigation such as subpoenas or search warrants to an Internet Service Provider to verify if someone was assigned an Internet Protocol address associated with the data posted. The courts will continue to review Internet-based data and apply the existing framework of laws around the data investigators collect.
Todd G. Shipley has more than 25 years of experience in law enforcement: from investigating financial and computer crimes to overseeing the training of high-tech crimes investigators. Between 2004 and 2007, he was the Director of Systems Security and High Tech Crime Prevention Training--and manager of the National Criminal Justice Computer Laboratory and Training Center--for SEARCH, The National Consortium for Justice Information and Statistics.