Autopsy User Documentation  4.14.0
Graphical digital forensics platform for The Sleuth Kit and other tools.
File Discovery

Overview

The file discovery tool shows images or videos that match a set of filters configured by the user. You can choose how to group and order your results in order to see the most relevant data first.

Prerequisites

We suggest running all ingest modules before launching file discovery, but if time is a factor the following are the modules that are the most important. You will see a warning if you open file discovery without running the File Type Identification Module and EXIF Parser Module.

Required ingest modules:

Optional ingest modules:

Running File Discovery

To launch file discovery, either click the "File Discovery" icon near the top of the Autopsy UI or go to "Tools", "File Discovery". There are three steps when setting up file discovery, which flow from the top of the panel to the bottom:

  1. Choose the file type
  2. Set up filters
  3. Choose how to group and sort the results

Once everything is set up, use the "Show" button at the bottom of the left panel to display your results. If you want to cancel a search in progress you can use the "Cancel" button.

fd_main.png

File Type

The first step is choosing whether you want to display images or videos. The file type is determined by the MIME type of the file, which is why the file_type_identification_page must be run to see any results. Switching between the file types will clear any results being displayed and reset the filters.

fd_fileType.png

Filtering

The second step is to select and configure your filters. For most filters, you enable them using the checkbox on the left and then select your options. Multiple options can be selected by using CTRL + left click. Files must pass all enabled filters to be displayed.

File Size Filter

The file size filter lets you restrict the size of your results. The options are different for images and videos - an extra small image might be under 16 KB while an extra small video is anything under 500 KB.

fd_fileSizeFilter.png

Data Source Filter

The data source filter lets you restrict which data sources in your case to include in the results.

fd_dataSourceFilter.png

Past Occurrences Filter

The past occurrences filter uses the central repository and known hash sets to restrict how commom/rare a file must be to be included in the results. By default, the "Known Files" option is disabled, meaning that any file matching the NSRL or other white-listed hash set will not be displayed.

fd_pastOccur.png

The counts for the rest of the options are based on how many data sources in your central repository contain a copy of this file (based on hash). If a file only appears in one data source in the current case, then it will match "Unique(1)". If it has only been seen in a few other data source, it will match "Rare(2-10)". Note that it doesn't matter how many times a file appears in each data source - a file could have twenty copies in one data source and still be "unique".

Possibly User Created

The possibly user created filter restricts the results to files that suspected to be raw images or videos.

fd_userCreatedFilter.png

This means the image or video must have a "User Content Suspected" result associated with it. These primarily come from the Exif parser module.

fd_userContentArtifact.png

Hash Set Filter

The hash set filter restricts the results to files found in the selected hash sets. Only notable hash sets that have hits in the current case are listed (though those hits may not be images or videos). See the Hash Lookup Module page for more information on creating and using hash sets.

fd_hashSetFilter.png

Interesting Item Filter

The interesting item filter restricts the results to files found in the selected interesting item rule sets. Only interesting file rule sets that have results in the current case are listed (though those matches may not be images or videos). See the Interesting Files Identifier Module page for more information on creating and using interesting item rule sets.

fd_interestingItemsFilter.png

Object Detected Filter

The object detected filter restricts the results to files that matched the selected classifiers. Only classifiers that have results in the current case are listed. Note that currently the built-in Object Detection ingest module only works on images, so you should generally not use this filter with videos. See the Object Detection page for more information on setting up classifiers.

fd_objectFilter.png

Parent Folder Filter

The parent folder filter either restricts the path the files can be on. This filter works differently than the others in that the individual options do not have to be selected - every rule that has been entered will be applied.

fd_parentFilter.png

You can enter paths that should be included and paths that should be ignored. For both you then specify whether the path string you entered is a full path or a substring. For full path matches you'll need to include the leading and trailing slashes. Full path matches are also case-sensitive.

The default options, shown above, will exclude any file that has a "Windows" folder or a "Program Files" folder in its path. It would exclude files like "/Windows/System32/image1.jpg" but would not exclude "/My Pictures/Bay Windows/image2.jpg" because the slashes around "Windows" force it to match the exact folder name.

Here is another example. This rule was created with "Full" and "Include" selected.

fd_parentEx2.png

This matches the file "/LogicalFileSet2/File Discovery/bird1.tif" but not any images in subfolders under "File Discovery".

When there are multiple path options in the filter, they will be applied as follows:

This allows you to, for example, make rules to include both the "My Documents" and the "My Pictures" folders.

Grouping and Sorting

The final options are for how you want to group and sort your results.

fd_grouping.png

The first option lets you choose the top level grouping for your results and the second option lets you choose how to sort them. The groups appear in the middle column of the file discovery panel. Note that some of the grouping options may not always appear - for example, grouping by past occurrences will only be present if the Central Repository is enabled, and grouping by hash set will only be present if there are hash set hits in your current case. The example below shows the groups created using the default options (group by file size, order groups by group name):

fd_groupingSize.png

In the case of file size and past occurrences, ordering by group name is based on the natural ordering of the group (largest to smallest or most rare to most common). For the other groups it will be alphabetical. Ordering groups by size will sort them based on how many files each group contains, going largest to smallest. For example, here we've grouped by interesting item set and ordered the groups by their size.

fd_groupingInt.png

The interesting items filter was not enabled so most images ended up in the "None" group, meaning they have no interesting file result associated with them. The final group in the list contains a file that matched both interesting item rule sets.

The last grouping and sorting option is choosing how to sort the results within a group. This is the order of the results in the top right panel after selecting a group from the middle column. Note that due to the merging of results with the same hash in that panel, ordering by file name, path, or data source can vary. See the De-duplication section below for more information.

Viewing Results

Overview

Once you select your options and click "Show", you'll see a list of groups in the middle panel. Selecting one of these groups will display the results from that group in the right panel. If your results are images, you'll see thumbnails for each image in the top area of the right panel.

fd_resultGroups.png

If your results are videos, each result will display four thumbnails from the video.

fd_videos.png

When you select a result from the top of the right panel, you'll see the path to the corresponding file(s) in the "Instances" panel below the thumbnails. There may be more than one file instance associated with a result - see the De-duplication section below. You can right-click on files in the instances panel to use most of options available in the normal Result Viewer.

fd_instanceContext.png

The bottom section of the panel is identical to the standard Content Viewer and displays data corresponding to the file instance selected in the middle of the panel.

De-duplication

Assuming the Hash Lookup Module module has been run, all files in a result group with the same hash will be merged together under a single instance. You can see the number of instances of each file under the thumbnail, and each file instance will be displayed in the middle section of the panel.

fd_dupeEx.png

Clicking on a particular instance will load data for that file in the content viewer area at the bottom.

Note that files in different groups will not be merged together or appear under the instances list of each other. For example, if you choose to group by parent folder and have two instances of a file with the same hash but in different folders, each will appear once under its parent folder. Grouping by file size (the default) will always merge every instance of the same file.

Status Icons

A number of icons may be displayed in the bottom right of the thumbnails to help point out notable results. Hovering over the icon will display a message explaining why the icon is present. In the image below, the yellow icon is present because the file is associated with an interesting item set.

fd_icon.png

Most of the icons match what would be displayed in the "S" column of the normal Result Viewer.

Icon Usage
yellow-circle-yield.png
Interesting file set match or normal file tag
red-circle-exclamation.png
Notable hash set hit or notable file tag
file-icon-deleted.png
Deleted file (every instance is deleted)

Paging

If the group you select has many results, the results will be split up into pages. You can use the left and right arrows to move between pages or type in the page number you wish to go to. You can adjust the number of results per page using the drop down box in the upper right.

fd_paging.png

Copyright © 2012-2020 Basis Technology. Generated on Sat Jan 18 2020
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