While no IT organization wants to have to undertake a digital investigation, should it need to do so one factor for success is to have well-thought-out procedures in place and appropriately trained personnel ready to adhere to them -- whether the purported crime involves an instant message sitting on a smartphone or customer data stolen in telecom fraud.
The National Institute of Justice's (NIJ) Office of Justice Programs offers a useful 74-page guide to digital investigations that IT organizations might find helpful in defining such procedures. The guide, called "Electronic Crime Scene Investigation: A Guide for First Responders, Second Edition," is for anyone charged with responsibility for protecting, recognizing, collecting, and preserving electronic evidence. In other words, it can prove of value not only to law enforcement and other first responders but also for CIOs, chief security officers and other IT professionals called on to investigate digital crime.
Digital Evidence: Knowing What's What
One thing I learned while working in military intelligence research and development is that everything can be useful information even if the data collected does not change over time. When conducting a digital investigation, that means you must collect, store, and process all the possible information without making assumptions of its value -- you never know when a piece of data will refer back to other data that seemed useless when first discovered.
Digital evidence, therefore, is information and data that is or might be of value to an investigation. It can be stored on, received by, or transmitted to most electronic devices, including portable/handheld devices such as cell phones, smartphones, personal digital assistants, digital audio/video multimedia devices, pagers, digital cameras, and global positioning system (GPS) receivers. Software applications, data, information, documents, e-mail messages, browsing history, chat logs, buddy lists, photographs, image files, videos, databases, and financial records can be valuable evidence in an investigation or prosecution.
You can think of digital evidence the same as a fingerprint, DNA, photograph, video, recording, or other form of stored information. That is, it's latent -- present and capable of emerging with the right tools and procedures but not evidently visible, obvious or active.
On the other hand, digital evidence can have a short useful life. Conditions may change so that the evidence is no longer useful. It can be time sensitive.
Collecting Digital Evidence
Before collecting evidence, IT investigators must ensure that they have legal and organizational authority to seize the evidence and that the authorities have secured and thoroughly documented the investigation scene. IT investigators must be careful and cautious when collecting, preserving, transporting, and storing digital evidence so as not to alter, damage or destroy the data. They must even be sure to wear protective gloves and antistatic clothing so as not to inadvertently affect the data.
After determining what is evidence, they must:
• Identify, seize and secure all digital evidence at the scene of the investigation, not later
• Document the entire investigated location and the specific evidence collected
• Collect, label and preserve the evidence in purpose-built bags that prevent changes via antistatic and radio frequency (RF) shielding
• Package and transport digital evidence in a secure manner that satisfies legal requirements for trail of evidence movement.
• Identify, seize and secure all digital evidence at the scene of the investigation, not later
• Document the entire investigated location and the specific evidence collected
• Collect, label and preserve the evidence in purpose-built bags that prevent changes via antistatic and radio frequency (RF) shielding
• Package and transport digital evidence in a secure manner that satisfies legal requirements for trail of evidence movement.
IT professionals who haven't been trained to deal with digital evidence should not attempt to explore the contents of or recover information from any electronic device other than to record its location and what is visible on the display screen. They must not press any keys or click the mouse.
Mobile devices can prove particularly troublesome. For example, digital evidence may be lost when the device loses power or be overwritten or deleted remotely while the device is powered up and not protected in an RF-proof bag. Users can buy software for smartphones, for example, that lets them remotely make the device unusable or the data it contains inaccessible if the phone is lost or stolen -- or gathered as evidence in a digital crime.
Tools of the Trade
Those investigating digital evidence should have the proper tools for the investigation. Many of the tools are obvious but some are forgotten or not considered at all.
The following list covers tools less commonly considered but nonetheless essential to a successful digital evidence investigation:
• Cameras (photo and video) for visually documenting the scene of the investigation
• Evidence inventory logs
• Antistatic bags to prevent evidence contamination
• Nonmagnetic tools to prevent evidence contamination
• RF-shielding material, including Faraday isolation bags or aluminum foil to wrap cell phones, smartphones and other mobile devices.
• Cameras (photo and video) for visually documenting the scene of the investigation
• Evidence inventory logs
• Antistatic bags to prevent evidence contamination
• Nonmagnetic tools to prevent evidence contamination
• RF-shielding material, including Faraday isolation bags or aluminum foil to wrap cell phones, smartphones and other mobile devices.
Dealing with Telecom Fraud
Digital investigations also come into play for telecommunications fraud, which can result in millions of dollars of false charges for enterprise and government organizations (read Telecom Fraud, Bigger than You Thought). Telecom fraud has become more pervasive and sophisticated as more means of communicating, especially via mobile devices and networks, have arrived.
The old TDM world was centrally controlled. Not so in the IP world. Besides outsiders perpetrating fraud, employees, dealers and sometimes operators have added risk to the telecom business. However, telecom managers and the providers have decreased their vigilance, not increased it. This reduction of vigilance appears to be one of the root causes of the success of telecom fraud.
Digital evidence in telecom fraud investigations includes:
• Desktop, laptop, tablet, e-reader and mobile computers
• Removable media
• External data storage devices
• Phone programming software
• Subscriber identity module (SIM) cards and readers
• Hacker boxes and cables
• Stolen telephones
• Erasable programmable read-only memory burners
• Desktop, laptop, tablet, e-reader and mobile computers
• Removable media
• External data storage devices
• Phone programming software
• Subscriber identity module (SIM) cards and readers
• Hacker boxes and cables
• Stolen telephones
• Erasable programmable read-only memory burners
Other data and documents include:
• Lists of customer database records
• Printed e-mail, notes and letters
• Financial asset records
• Information regarding Internet activity
• Telephone programming manuals
• Lists of customer database records
• Printed e-mail, notes and letters
• Financial asset records
• Information regarding Internet activity
• Telephone programming manuals
Learning From Investigations
Digital crime is here to stay. As enterprises and governments find ways to stop malicious behavior, perpetrators invent new ways to invade networks and devices. Developing and using investigation tools and procedures will dampen the efforts of those invading networks and devices but may never fully stop the intrusions. Fast investigations that discover weaknesses can mitigate the losses.
Digital investigations are just as important as the methods used to prevent intrusions. Eenterprise and government organizations cannot rely on prevention alone. Learning from the investigations will help strengthen the prevention methods.
