Here are 20 of the best free tools that will help you conduct a digital forensic investigation. Whether it’s for an internal human resources case, an investigation into unauthorized access to a server, or if you just want to learn a new skill, these suites and utilities will help you conduct memory forensic analysis, hard drive forensic analysis, forensic image exploration, forensic imaging and mobile forensics. As such, they all provide the ability to bring back in-depth information about what’s “under the hood” of a system.
This is by no means an extensive list and may not cover everything you need for your investigation. You might also need additional utilities such a file viewers, hash generators, and text editors – checkout 101 Free Admin Tools for some of these.
My articles on Top 10 Free Troubleshooting Tools for SysAdmins, Top 20 Free Network Monitoring and Analysis Tools for Sys Admins and Top 20 Free File Management Tools for Sys Admins might also come in handy since they contain a bunch of tools that can be used for Digital Forensic Investigations (e.g. BackTrack and the SysInternals Suite or the NirSoft Suite of tools).
Even if you may have heard of some of these tools before, I’m confident that you’ll find a gem or two amongst this list.
The SANS Investigative Forensic Toolkit (SIFT) is an Ubuntu based Live CD which includes all the tools you need to conduct an in-depth forensic or incident response investigation. It supports analysis of Expert Witness Format (E01), Advanced Forensic Format (AFF), and RAW (dd) evidence formats. SIFT includes tools such as log2timeline for generating a timeline from system logs, Scalpel for data file carving, Rifiuti for examining the recycle bin, and lots more.
When you first boot into the SIFT environment, I suggest you explore the documentation on the desktop to help you become accustomed to what tools are available and how to use them. There is also a good explanation of where to find evidence on a system. Use the top menu bar to open a tool, or launch it manually from a terminal window.
CrowdResponse is a lightweight console application that can be used as part of an incident response scenario to gather contextual information such as a process list, scheduled tasks, or Shim Cache. Using embedded YARA signatures you can also scan your host for malware and report if there are any indicators of compromise.
To run CrowdsResponse, extract the ZIP file and launch a Command Prompt with Administrative Privileges. Navigate to the folder where the CrowdResponse*.exe process resides and enter your command parameters. At minimum, you must include the output path and the ‘tool’ you wish to use to collect data. For a full list of ‘tools’, enter CrowdResponse64.exe in the command prompt and it will bring up a list of supported tool names and example parameters.
Once you’ve exported the data you need, you can use CRconvert.exe to convert the data from XML to another file format like CSV or HTML.
Volatility is a memory forensics framework for incident response and malware analysis that allows you to extract digital artefacts from volatile memory (RAM) dumps. Using Volatility you can extract information about running processes, open network sockets and network connections, DLLs loaded for each process, cached registry hives, process IDs, and more.
If you are using the standalone Windows executable version of Volatility, simply place volatility-2.x.standalone.exe into a folder and open a command prompt window. From the command prompt, navigate to the location of the executable file and type “volatility-2.x.standalone.exe –f <FILENAME> –profile=<PROFILENAME> <PLUGINNAME>” without quotes – FILENAME would be the name of the memory dump file you wish to analyse, PROFILENAME would be the machine the memory dump was taken on and PLUGINNAME would be the name of the plugin you wish to use to extract information.
Note: In the example above I am using the ‘connscan’ plugin to search the physical memory dump for TCP connection information.
The Sleuth Kit is an open source digital forensics toolkit that can be used to perform in-depth analysis of various file systems. Autopsy is essentially a GUI that sits on top of The Sleuth Kit. It comes with features like Timeline Analysis, Hash Filtering, File System Analysis and Keyword Searching out of the box, with the ability to add other modules for extended functionality.
Note: You can use The Sleuth Kit if you are running a Linux box and Autopsy if you are running a Windows box.
When you launch Autopsy, you can choose to create a new case or load an existing one. If you choose to create a new case you will need to load a forensic image or a local disk to start your analysis. Once the analysis process is complete, use the nodes on the left hand pane to choose which results to view.
FTK Imager is a data preview and imaging tool that allows you to examine files and folders on local hard drives, network drives, CDs/DVDs, and review the content of forensic images or memory dumps. Using FTK Imager you can also create SHA1 or MD5 hashes of files, export files and folders from forensic images to disk, review and recover files that were deleted from the Recycle Bin (providing that their data blocks haven’t been overwritten), and mount a forensic image to view its contents in Windows Explorer.
Note: There is a portable version of FTK Imager that will allow you to run it from a USB disk.
When you launch FTK Imager, go to ‘File > Add Evidence Item…’ to load a piece of evidence for review. To create a forensic image, go to ‘File > Create Disk Image…’ and choose which source you wish to forensically image.
06 Linux ‘dd’
dd comes by default on the majority of Linux distributions available today (e.g. Ubuntu, Fedora). This tool can be used for various digital forensic tasks such as forensically wiping a drive (zero-ing out a drive) and creating a raw image of a drive.
Note: dd is a very powerful tool that can have devastating effects if not used with care. It is recommended that you experiment in a safe environment before using this tool in the real world.
Tip: A modified version of dd is available from http://sourceforge.net/projects/dc3dd/ – dc3dd includes additional features that were added specifically for digital forensic acquisition tasks.
To use dd, simply open a terminal window and type dd followed by a set of command parameters (which command parameters will obviously depend on what you want to do). The basic dd syntax for forensically wiping a drive is:
dd if=/dev/zero of=/dev/sdb1 bs=1024
where if = input file, of = output file, bs = byte size
Note: Replace /dev/sdb1 with the drive name of the drive you want to forensically wipe and 1024 with the size of the byte blocks you want to write out.
The basic dd syntax for creating a forensic image of a drive is:
dd if=/dev/sdb1 of=/home/andrew/newimage.dd bs=512 conv=noerror,sync
where if = input file (or in this case drive), of = output file, bs = byte size, conv = conversion options
Tip: For additional usage info, from a terminal window, type “man dd” without quotes to bring up the help manual for the dd command.
CAINE (Computer Aided INvestigative Environment) is Linux Live CD that contains a wealth of digital forensic tools. Features include a user-friendly GUI, semi-automated report creation and tools for Mobile Forensics, Network Forensics, Data Recovery and more.
When you boot into the CAINE Linux environment, you can launch the digital forensic tools from the CAINE interface (shortcut on the desktop) or from each tool’s shortcut in the ‘Forensic Tools’ folder on the applications menu bar.
ExifTool is a command-line application used to read, write or edit file metadata information. It is fast, powerful and supports a large range of file formats (although image file types are its speciality). ExifTool can be used for analysing the static properties of suspicious files in a host-based forensic investigation, for example.
To use ExifTool, simply drag and drop the file you want to extract metadata from onto the exiftool(-k).exe application and it will open a command prompt window with the information displayed. Alternatively, rename exiftool(-k).exe to exiftool.exe and run from the command prompt.
Free Hex Editor Neo is a basic hex editor that was designed to handle very large files. While a lot of the additional features are found in the commercial versions of Hex Editor Neo, I find this tool useful for loading large files (e.g. database files or forensic images) and performing actions such as manual data carving, low-level file editing, information gathering, or searching for hidden data.
Use ‘File > Open’ to load a file into Hex Editor Neo. The data will appear in the middle window where you can begin to navigate through the hex manually or press CTRL + F to run a search.
bulk_extractor is a computer forensics tool that scans a disk image, file, or directory of files and extracts information such as credit card numbers, domains, e-mail addresses, URLs, and ZIP files. The extracted information is output to a series of text files (which can be reviewed manually or analysed using other forensics tools or scripts).
Tip: Within the output text files you will find entries for data that resemble a credit card number, e-mail address, domain name, etc. You will also see a decimal value in the first column of the text file that, when converted to hex, can be used as the pointer on disk where the entry was found (i.e. if you were analysing the disk manually using a hex editor for example, you would jump to this hexadecimal value to view the data).
Bulk_extractor comes as a command-line tool or a GUI tool. In the example above I set the bulk extractor tool to extract information from a forensics image I took earlier and output the results to a folder called “BE_Output”. The results can then be viewed in the Bulk Extractor Viewer and the output text files mentioned above.
DEFT is another Linux Live CD which bundles some of the most popular free and open source computer forensic tools available. It aims to help with Incident Response, Cyber Intelligence and Computer Forensics scenarios. Amongst others, it contains tools for Mobile Forensics, Network Forensics, Data Recovery, and Hashing.
When you boot using DEFT, you are asked whether you wish to load the live environment or install DEFT to disk. If you load the live environment you can use the shortcuts on the application menu bar to launch the required tools.
Xplico is an open source Network Forensic Analysis Tool (NFAT) that aims to extract applications data from internet traffic (e.g. Xplico can extract an e-mail message from POP, IMAP or SMTP traffic). Features include support for a multitude of protocols (e.g. HTTP, SIP, IMAP, TCP, UDP), TCP reassembly, and the ability to output data to a MySQL or SQLite database, amongst others.
Once you’ve installed Xplico, access the web interface by navigating to http://<IPADDRESS>:9876 and logging in with a normal user account. The first thing you need to do is create a case and add a new session. When you create a new session you can either load a PCAP file (acquired from Wireshark for example) or start a live capture. Once the session has finished decoding, use the navigation menu on the left hand side to view the results.
I briefly touched on LastActivityView when pointing out the NirSoft suite of tools in my Top 10 Free System Troubleshooting Tools for SysAdmins article. LastActivityView allows you to view what actions were taken by a user and what events occurred on the machine. Any activities such as running an executable file, opening a file/folder from Explorer, an application or system crash or a user performing a software installation will be logged. The information can be exported to a CSV / XML / HTML file. This tool is useful when you need to prove that a user (or account) performed an action he or she said they didn’t.
When you launch LastActivityView, it will immediately start displaying a list of actions taken on the machine it is being run on. Sort by action time or use the search button to start investigating what actions were taken on the machine.
DSi USB Write Blocker is a software based write blocker that prevents write access to USB devices. This is important in an investigation to prevent modifying the metadata or timestamps and invalidating the evidence.
When you run DSi USB Write Blocker, it brings up a window that allows you to enable or disable the USB Write Blocker. Once you make changes and exit the application, you can keep an eye on the status from the padlock icon in the taskbar. When performing an analysis of a USB drive, enable the USB Write Blocker first and then plug the USB drive in.
If you are looking for a command line alternative, check out ‘USB Write Blocker for ALL Windows’. This tool works by updating a registry entry to prevent USB drives from being written to. To run the tool, you simply execute the batch file and select Option 1 to put the USB ports into read-only mode.
RedLine offers the ability to perform memory and file analysis of a specific host. It collects information about running processes and drivers from memory, and gathers file system metadata, registry data, event logs, network information, services, tasks, and Internet history to help build an overall threat assessment profile.
When you launch RedLine, you will be given a choice to Collect Data or Analyze Data. Unless you already have a memory dump file available, you’ll need to create a collector to gather data from the machine and let that process run through to completion. Once you have a memory dump file to hand you can begin your analysis.
PlainSight is a Live CD based on Knoppix (a Linux distribution) that allows you to perform digital forensic tasks such as viewing internet histories, data carving, USB device usage information gathering, examining physical memory dumps, extracting password hashes, and more.
When you boot into PlainSight, a window pops up asking you to select whether you want to perform a scan, load a file or run the wizard. Enter a selection to begin the data extraction and analysis process.
HxD is one of my personal favourites. It is a user-friendly hex editor that allows you to perform low-level editing and modifying of a raw disk or main memory (RAM). HxD was designed with easy-of-use and performance in mind and can handle large files without issue. Features include searching and replacing, exporting, checksums/digests, an in-built file shredder, concatenation or splitting of files, generation of statistics and more.
From the HxD interface start your analysis by opening a file from ‘File > Open’, loading a disk from ‘Extras > Open disk…’ or loading a RAM process from ‘Extras > Open RAM…’
HELIX3 is a Live CD based on Linux that was built to be used in Incident Response, Computer Forensics and E-Discovery scenarios. It is packed with a bunch of open source tools ranging from hex editors to data carving software to password cracking utilities, and more.
Note: The HELIX3 version you need is 2009R1. This version was the last free version available before HELIX was taken over by a commercial vendor. HELIX3 2009R1 is still valid today and makes for a useful addition to your digital forensics toolkit.
When you boot using HELIX3, you are asked whether you want to load the GUI environment or install HELIX3 to disk. If you choose to load the GUI environment directly (recommended), a Linux-based screen will appear giving you the option to run the graphical version of the bundled tools.
Paladin Forensic Suite is a Live CD based on Ubuntu that is packed with wealth of open source forensic tools. The 80+ tools found on this Live CD are organized into over 25 categories including Imaging Tools, Malware Analysis, Social Media Analysis, Hashing Tools, etc.
After you boot Paladin Forensic Suite, navigate to the App Menu or click on one of the icons in the taskbar to get started.
Note: A handy Quick Start Guide for Paladin Forensic Suite is available to view or download from the Paladin website as well as the taskbar within Paladin itself.
USB Historian parses USB information, primarily from the Windows registry, to give you a list of all USB drives that were plugged into the machine. It displays information such as the name of the USB drive, the serial number, when it was mounted and by which user account. This information can be very useful when you’re dealing with an investigation whereby you need to understand if data was stolen, moved or accessed.
When you launch USB Historian, click the ‘+’ icon on the top menu to launch the data parse wizard. Select which method you want to parse data from (Drive Letter, Windows and Users Folder, or Individual Hives/Files) and then select the respective data to parse. Once complete you will see information similar to that shown in the above image.