What is Autopsy
Autopsy is an open source forensics tool that can be compared to FTK or EnCase and is able to assist investigators when working on cases. It is created by Brian Carrier, the same person who made the Sleuth Kit which Autopsy is based off of.
What is New in Version 3
Autopsy 3 has been completely rewritten from version 2 and includes many new tools and options that previous versions did not have. Autopsy 2 was a browser based tool, which meant that it ran through a web browser, specifically Mozilla’s Firefox. Version 3 has changed to be a self-reliant program that does not need to be run through Firefox and has the look and feel of a traditional forensic program. Autopsy 3 also has included a new function called ingest modules that analyze data, list the information in tree format, and allow searches based on: keywords, hashes, and recent activity. Investigators who have used older versions of Autopsy will notice the restructuring of the program and the addition of the single navigation tree that creates a cleaner and streamlined look.
Where to Get Autopsy 3.0
Autopsy 3.0 can be acquired from different sources, but the most reliable source is to go to the website for the Sleuth Kit (http://www.sleuthkit.org) and select the projects tab at the top:
Next navigate to the Autopsy page by selecting Autopsy on the side bar.
Select Download followed by “Download Beta Version 3.0.0b4 (July 3, 2012), or the newest release available of Version 3.
You will be taken to the Sourceforge site for the Autopsy browser and given a list of versions to download. Select the newest version available to download and it will automatically start after a five second delay. After Autopsy has been downloaded, run the installer and then Autopsy will be ready for use.
How to Start a Case
Starting a case in Autopsy 3 is simple and easy to learn for anyone ranging from forensics investigators all the way to curious users or IT support. Upon starting Autopsy 3, a window will open with three selections to make: create a new case, open existing case, or to open a recent case.
For this tutorial we will select the “Create New Case” option and be directed to a new window that will have information to fill in, and for this tutorial we will be naming the case “Test.”
After the information has been filled in select the next button. The next window will allow the investigator to fill in the case number and examiner name. This is for the purpose of creating better documentation and logging. After the information is filled in select the finish button to continue.
The next step in the investigation will be to add an image file to the case. The image file can be chosen from a wide variety of formats including: img, dd, 001, aa, and e01. Use the browse button to find the image that is desired to work with and select add. Options to choose the timezone of where the image came from as well as to ignore orphan files in FAT file systems are available to be selected based on the investigators preference and situation. For this tutorial I am using the Forensics World C.S.I. Challenge sample image called precious.img. If you would like to follow along with the tutorial and use the same image for practice you can obtain the image from: (http://myweb.cwpost.liu.edu/cmalinow/csi/tools.html).
After selecting the next button the image will be added to the case and the next button should be selected again if there are no errors.
The following window will bring the investigator to the Ingest wizard panel, which is one of the new features offered in Autopsy. There are three options in the first box: Recent Activity, Hash lookup, and Keyword Searches.
By selecting any of the options advanced settings can be set to increase the capabilities of the search. Under the Hash Lookup option there is the advanced option to add databases of known hashes.
Under the Keyword Search option are many different lists that can be used to search for information. By default, Phone Numbers, IP Addresses, Email Addresses, and URL’s are available. Select the Advanced button and a Keyword List Configuration window will open. In this new window select New List and type the name that is desired for the list. This makes it easier to search by subject matter or other organizational methods. For now the list Test keywords will be used to create a list. In the adjacent pane there is a blank section with a word bar and an Add button next to it. Type the keyword desired (case sensitive) and select Add to add the word to the list. There is also the option to select Regular Expression. This allows the investigator to further narrow the field to search in by selecting what the keyword is that is being searched for including: passwords, emails, text file name, domains, and many more options.
For this tutorial the keywords that are used are chosen because of the content in the image that is being used so the best results will be found.
After finishing the keyword parameters the screen will be laid out for the user.
Notice how everything is laid out in “tree” format much like in the popular programs such as EnCase. This is one of the new features in 3.0 and is helpful as it allows the investigator to organize much easier. After the image is indexed the tree will be populated by the file system, extracted content, keyword searches, and the hash list (if any were used).
One of the first things the investigator should do is to generate a report. This will allow the investigator to have an idea of what type of information is available and what to expect. The report can be generated in three formats: Excel, XML, and HTML. It also has the ability to select what information to display with choices that can be seen in the image below.
With the report on hand the investigator will have an idea of what to expect as well as a list of programs that are installed on the machine. This will allow the investigator to look for specific files or keep an eye out for certain markers. For example, if TrueCrypt is installed on the computer then the investigator will know that there is a chance of a TrueCrypt volume on the computer and can look for it. Another example of using reports is to look at the attached device list and compare that to removable media that was also seized. This can help investigators gather all the evidence they need to perform a complete investigation.
Looking at the tree, the top selection is titled “Images” this is where the acquired image is located and the bulk of the investigation, will take place. If the Images tab is expanded the investigator will see each image that was added to the investigation. By expanding an images tab the volumes of the image will be seen including the file system and unallocated space. Expanding the tab that contains the Operating System will give the investigator a look at the root directory and the tree that contains most of the relevant information. This is the same as if the investigator would open the default drive when browsing through a system.
Below the Images tab is the “Views” tab that will allow the investigator to separate the information in the image into different categories such as by file types and by recent documents. The file type can be broken down into: images, video, audio, and documents which includes the major text formats. Another section in the Views tab is a new feature in Autopsy 3, the Recent Files tab. This tab allows the investigator to get a rough outline of what happened in the last 6 days of use by the suspect. The results include registry files, documents opened, and programs run.
The next tab that is seen is the Results tab, this is a new feature that displays all the information from the ingest process. This uses the program BEViewer to look for certain information inside of the data and separate it into sections that make it easier to search for specific data instead of going through all of the information manually. Although this simplifies the investigation process, it does not mean that this is all of the information that is able to be gained through an investigation.
There are 4 main categories when separating the Results tab: Extracted Content, Keyword Hits, Hashset Hits, and E-mail Messages. Each of these sections has subsections that allow for more specific information divisions. In the Extracted Content tab there are sections for: Bookmarks, Cookies, Web History, Downloads, Recent Documents, Installed Programs, and Device Attached.
The bookmarks tab contains information on bookmarks created in the internet browsers so the investigator can see a list of sites that the suspect frequented enough to create a bookmark for. The cookies tab will allow investigators to see a general idea of where the suspect has been recently by looking through the cookies and seeing which sites have cookies stored on the computer. The Web history tab searches for .dat files and lists them to show another list of internet usage through web browsers. The download tab allows for the search for any downloads on the suspect computer. Recent documents will show documents that were opened on the machine recently by looking at their metadata and deciding how long ago a document was opened. The installed programs tab will give the investigator a list of programs that are currently installed on the machine. The tab for attached devices is obtained by looking through the registry files and determining which hardware devices have been plugged into the system at one point or another.
Under the keyword hits tab the investigator will see all the options that were selected in the ingest index window when starting the case. The information includes: phone numbers, URLs, email addresses, search words by the user, IP addresses, and regular expression searches.
The tab for hashset hits only has results if a list library was added to the case before hand to run matches against. If the investigators had a hash library of known child pornography or pirated material they could run all the information on the computer against the library and all of the results would be placed in the hashset hits tab.
The e-mail message tab will place any emails from a desktop client in the tab for review. The supported programs are Microsoft Outlook and Mozilla Thunderbird as of now but more are scheduled for support in the future.