Windows 7 Registry Forensics

How is management going to handle this situation? A typical approach would be to confront the workers. However, they most likely would deny any wrongdoing and probably try to obfuscate any potential evidence. Probably the best approach would be to covertly triage the live computers and perform post-mortem examinations of their hard drives. Frequently a business or corporation’s IT department members will lack the necessary qualifications or experience to perform these types of forensic examinations. This is not uncommon since IT personnel normally are not trained as forensic examiners.

Usually management will have to contract with an external digital forensics consulting firm to provide the services. In today’s world, it has become essential that management have processes in place (i.e. a plan) such that when an intrusion occurs or employee misconduct is alleged, they will have a firm foundation to support and assist with any potential civil or criminal proceedings. Failure to do so can have a detrimental effect upon the business or corporation.

A Windows computer system has several forensically important areas where probative information can be found: in the computer’s RAM (if the system is live), in the Registry, or on the computer’s hard drive. The examination and extraction of probative information from a live computer system involves the use of triage tools which themselves will make changes to those same forensically important areas! Although this violates the “golden rule” of digital forensics, in some circumstances there is no alternative. Presuming that examiners have previously verified the functionality of their triage tools, they should have a fairly good understanding, and be able to document, what changes are made to a live computer system when they use those tools.

Unless they are involved in incident response, examiners are not often confronted with having to image a live system. Normally they would forensically image computer hard drives post-mortem, in a controlled work environment. The image would then be examined for probative information. Most forensic tools incorporate automated built-in features such as recovering deleted folders, performing keyword searches, carving data from unallocated space, searching directories and files, and so forth. Automated features are a necessity as it would be extremely labor intensive for an examiner to manually search a hard drive. In today’s digital forensics environment, examiners must have specialized training, knowledge, skills, abilities, tools, and experience to ensure reliable and repeatable results when triaging either a live system or examining a computer hard drive post-mortem.

What Is the Windows Registry and What Does It Do?
Early Windows operating systems included a “WIN.INI” file (which controlled the desktop and all applications on the computer system) and a “SYSTEM.INI” file (which controlled the computer’s hardware). They also used the configuration files “config.sys” (which loaded device drivers) and “autoexec.bat” (which ran startup programs and set environment variables). When Windows 3.1 was introduced, it was initially targeted to the corporate work environment. One of the assumptions made was that very few Windows applications would be installed on each computer. This would then limit the number of stored system and application settings. Since program developers still needed to store application specific settings, they used individual “.ini” human readable text files which were linked to the “WIN.INI” file. These were generally organized in groups located in a shared location. However, there were a number of drawbacks to this practice: it did not allow for user-specific settings in a multi-use environment; there were no rules placed upon their storage by the operating system; their proliferation and storage anywhere on the hard drive made it difficult or virtually impossible to manage and optimize their performance; and their size limitations and slow access often hindered system operation.

The release of Windows 95 introduced a new concept, the “Registry.” Its purpose was to store all application settings in a standardized binary format in a centralized location and replace text-based configuration and “.ini” files. Because it provided one unified solution for accessing both system and application settings, the Registry was initially praised by developers, users, and administrators. Its advantages included: the binary format allowing for more efficient file parsing; Registry settings loading from user-specific paths; permitting multiple users to share the same computer; accessing a computer remotely, allowing for ease of backups and restorations. However, the introduction of the Registry created another whole set of unintended consequences: it now became more difficult to back up and recover individual applications; automated installers and uninstallers became more complex because configuration settings had to be created by the applications; a damaged or corrupted Registry might fail to load the device drivers necessary to boot the system. With the continuing requirements and demands of complex applications and network solutions, each iteration of the Windows Registry has grown larger and more complex.

The Microsoft Computer Dictionary, Fifth Edition, defines the Registry as: “A central hierarchical database used in Microsoft Windows 9x, Windows CE, Windows NT, and Windows 2000 used to store information that is necessary to configure the system for one or more users applications and hardware devices.” Windows XP, Windows Vista, and Windows 7 also contain a Registry. Although referred to as a “central hierarchical database,” the Registry is in fact a collection of files that are located in the “C:\Windows\System32\config” and “C:\Users\(Username)\” directories (Windows 7). The Registry contains information that Windows continually references such as the applications installed on the computer, the user profiles, the hardware on or attached to the system, property sheet folder settings, the ports being used, application icons, and so on. From a forensic perspective, the Registry is a gold mine that can often provide probative information to an investigator. For instance, some of the information that can be found in the Registry includes:
  • All the wireless networks that the computer has connected to
  • Recent search terms
  • Lists of the most recently used files or applications
  • Autorun locations that list applications to automatically run when the computer is booted
  • Contents of the User(s) desktop
  • All USB storage devices that have been attached to the computer
  • Malware (if it has installed itself as a service)
  • The directory structure and file names contained on external devices that have been attached to the computer (pre-Windows 7)
While the Windows Registry is forensically important, frequently it is not captured during the triage of a live system. Similarly, it is often overlooked during post-mortem examinations. Daily, examiners are faced with many challenges: a lack of training to perform triage on a live system; examining multiple hard drives containing terabytes of data; dealing with pressures from management to complete an arbitrary, often unrealistic, quota of examinations per month; constantly juggling and prioritizing overwhelming case loads; shortages of personnel; and until recently, limited tools for examining Registry files. When faced with these challenges, it is easy to understand why the Registry is not often forensically examined.


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