Kaiju : A Binary Analysis Framework Extension For The Ghidra Software Reverse Engineering Suite

CERT Kaiju is a collection of binary analysis tools for Ghidra. This is a Ghidra/Java implementation of some features of the CERT Pharos Binary Analysis Framework, particularly the function hashing and malware analysis tools, but is expected to grow new tools and capabilities over time.

As this is a new effort, this implementation does not yet have full feature parity with the original C++ implementation based on ROSE; however, the move to Java and Ghidra has actually enabled some new features not available in the original framework — notably, improved handling of non-x86 architectures. Since some significant re-architecting of the framework and tools is taking place, and the move to Java and Ghidra enables different capabilities than the C++ implementation, the decision was made to utilize new branding such that there would be less confusion between implementations when discussing the different tools and capabilities.

Our intention for the near future is to maintain both the original Pharos framework as well as Kaiju, side-by-side, since both can provide unique features and capabilities.

CAVEAT: As a prototype, there are many issues that may come up when evaluating the function hashes created by this plugin. For example, unlike the Pharos implementation, Kaiju’s function hashing module will create hashes for very small functions (e.g., ones with a single instruction like RET causing many more unintended collisions). As such, analytical results may vary between this plugin and Pharos fn2hash.

Quick Installation

Pre-built Kaiju packages are available. Simply download the ZIP file corresponding with your version of Ghidra and install according to the instructions below. It is recommended to install via Ghidra’s graphical interface, but it is also possible to manually unzip into the appropriate directory to install.

CERT Kaiju requires the following runtime dependencies:

• Ghidra 9.1+ (9.2+ recommended)
• Java 11+ (we recommend OpenJDK 11)

NOTE: It is also possible to build the extension package on your own and install it. Please see the instructions under the “Build Kaiju Yourself” section below.

Graphical Installation

Start Ghidra, and from the opening window, select from the menu: File > Install Extension. Click the plus sign at the top of the extensions window, navigate and select the .zip file in the file browser and hit OK. The extension will be installed and a checkbox will be marked next to the name of the extension in the window to let you know it is installed and ready.

The interface will ask you to restart Ghidra to start using the extension. Simply restart, and then Kaiju’s extra features will be available for use interactively or in scripts.

Some functionality may require enabling Kaiju plugins. To do this, open the Code Browser then navigate to the menu File > Configure. In the window that pops up, click the Configure link below the “CERT Kaiju” category icon. A pop-up will display all available publicly released Kaiju plugins. Check any plugins you wish to activate, then hit OK. You will now have access to interactive plugin features.

If a plugin is not immediately visible once enabled, you can find the plugin underneath the Window menu in the Code Browser.

Experimental “alpha” versions of future tools may be available from the “Experimental” category if you wish to test them. However these plugins are definitely experimental and unsupported and not recommended for production use. We do welcome early feedback though!

Manual Installation

Ghidra extensions like Kaiju may also be installed manually by unzipping the extension contents into the appropriate directory of your Ghidra installation. For more information, please see The Ghidra Installation Guide.

Usage

Kaiju’s tools may be used either in an interactive graphical way, or via a “headless” mode more suited for batch jobs. Some tools may only be available for graphical or headless use, by the nature of the tool.

Interactive Graphical Interface

Kaiju creates an interactive graphical interface (GUI) within Ghidra utilizing Java Swing and Ghidra’s plugin architecture.

Most of Kaiju’s tools are actually Analysis plugins that run automatically when the “Auto Analysis” option is chosen, either upon import of a new executable to disassemble, or by directly choosing Analysis > Auto Analyze... from the code browser window. You will see several CERT Analysis plugins selected by default in the Auto Analyze tool, but you can enable/disable any as desired.

The Analysis tools must be run before the various GUI tools will work, however. In some corner cases, it may even be helpful to run the Auto Analysis twice to ensure all of the metadata is produced to create correct partitioning and disassembly information, which in turn can influence the hashing results.

Analyzers are automatically run during Ghidra’s analysis phase and include:

• DisasmImprovements = improves the function partitioning of the disassembly compared to the standard Ghidra partitioning.
• Fn2Hash = calculates function hashes for all functions in a program and is used to generate YARA signatures for programs.

The GUI tools include:

• Function Hash Viewer = a plugin that displays an interactive list of functions in a program and several types of hashes. Analysts can use this to export one or more functions from a program into YARA signatures.
  • Select Window > CERT Function Hash Viewer from the menu to get started with this tool if it is not already visible. A new window will appear displaying a table of hashes and other data. Buttons along the top of the window can refresh the table or export data to file or a YARA signature. This window may also be docked into the main Ghidra CodeBrowser for easier use alongside other plugins. More extensive usage documentation can be found in Ghidra’s Help > Contents menu when using the tool.
• OOAnalyzer JSON Importer = a plugin that can load, parse, and apply Pharos-generated OOAnalyzer results to object oriented C++ executables in a Ghidra project. When launched, the plugin will prompt the user for the JSON output file produced by OOAnalyzer that contains information about recovered C++ classes. After loading the JSON file, recovered C++ data types and symbols found by OOAnalyzer are updated in the Ghidra Code Browser. The plugin’s design and implementation details are described in our SEI blog post titled Using OOAnalyzer to Reverse Engineer Object Oriented Code with Ghidra.
  • Select CERT > OOAnalyzer Importer from the menu to get started with this tool. A simple dialog popup will ask you to locate the JSON file you wish to import. More extensive usage documentation can be found in Ghidra’s Help > Contents menu when using the tool.

Command-line “Headless” Mode

Ghidra also supports a “headless” mode allowing tools to be run in some circumstances without use of the interactive GUI. These commands can therefore be utilized for scripting and “batch mode” jobs of large numbers of files.

The headless tools largely rely on Ghidra’s GhidraScript functionality.

Headless tools include:

• fn2hash = automatically run Fn2Hash on a given program and export all the hashes to a CSV file specified
• fn2yara = automatically run Fn2Hash on a given program and export all hash data as YARA signatures to the file specified
• fnxrefs = analyze a Program and export a list of Functions based on entry point address that have cross-references in data or other parts of the Program

A simple shell launch script named kaijuRun has been included to run these headless commands for simple scenarios, such as outputing the function hashes for every function in a single executable. Assuming the GHIDRA_INSTALL_DIR variable is set, one might for example run the launch script on a single executable as follows:

$GHIDRA_INSTALL_DIR/Ghidra/Extensions/kaiju/kaijuRun fn2hash example.exe

This command would output the results to an automatically named file as example.exe.Hashes.csv.

Basic help for the kaijuRun script is available by running:

$GHIDRA_INSTALL_DIR/Ghidra/Extensions/kaiju/kaijuRun –help

Please see docs/HeadlessKaiju.md file in the repository for more information on using this mode and the kaijuRun launcher script.

Further Documentation And Help

More comprehensive documentation and help is available, in one of two formats.

See the docs/ directory for Markdown-formatted documentation and help for all Kaiju tools and components. These documents are easy to maintain and edit and read even from a command line.

Alternatively, you may find the same documentation in Ghidra’s built-in help system. To access these help docs, from the Ghidra menu, go to Help > Contents and then select CERT Kaiju from the tree navigation on the left-hand side of the help window.

Please note that the Ghidra Help documentation is the exact same content as the Markdown files in the docs/ directory; thanks to an in-tree gradle plugin, gradle will automatically parse the Markdown and export into Ghidra HTML during the build process. This allows even simpler maintenance (update docs in just one place, not two) and keeps the two in sync.

All new documentation should be added to the docs/ directory.

Building Kaiju Yourself Using Gradle

Alternately to the pre-built packages, you may compile and build Kaiju yourself.

Build Dependencies

CERT Kaiju requires the following build dependencies:

• Ghidra 9.1+ (9.2+ recommended)
• gradle 6.4+ (latest gradle 6.x recommended, 7.x not supported)
• GSON 2.8.6
• Java 11+ (we recommend OpenJDK 11)

NOTE ABOUT GRADLE: Please ensure that gradle is building against the same JDK version in use by Ghidra on your system, or you may experience installation problems.

NOTE ABOUT GSON: In most cases, Gradle will automatically obtain this for you. If you find that you need to obtain it manually, you can download gson-2.8.6.jar and place it in the kaiju/lib directory.

Build Instructions

Once dependencies are installed, Kaiju may be built as a Ghidra extension by using the gradle build tool. It is recommended to first set a Ghidra environment variable, as Ghidra installation instructions specify.

In short: set GHIDRA_INSTALL_DIR as an environment variable first, then run gradle without any options:

export GHIDRA_INSTALL_DIR=<Absolute path to Ghidra install dir>
gradle

NOTE: Your Ghidra install directory is the directory containing the ghidraRun script (the top level directory after unzipping the Ghidra release distribution into the location of your choice.)

If for some reason your environment variable is not or can not be set, you can also specify it on the command like with:

gradle -PGHIDRA_INSTALL_DIR=<Absolute path to Ghidra install dir>

In either case, the newly-built Kaiju extension will appear as a .zip file within the dist/ directory. The filename will include “Kaiju”, the version of Ghidra it was built against, and the date it was built. If all goes well, you should see a message like the following that tells you the name of your built plugin.

Created ghidra_X.Y.Z_PUBLIC_YYYYMMDD_kaiju.zip in /kaiju/dist

where X.Y.Z is the version of Ghidra you are using, and YYYYMMDD is the date you built this Kaiju extension.

Optional: Running Tests With AUTOCATS

While not required, you may want to use the Kaiju testing suite to verify proper compilation and ensure there are no regressions while testing new code or before you install Kaiju in a production environment.

In order to run the Kaiju testing suite, you will need to first obtain the AUTOCATS (AUTOmated Code Analysis Testing Suite). AUTOCATS contains a number of executables and related data to perform tests and check for regressions in Kaiju. These test cases are shared with the Pharos binary analysis framework, therefore AUTOCATS is located in a separate git repository.

Clone the AUTOCATS repository with:

git clone https://github.com/cmu-sei/autocats

We recommend cloning the AUTOCATS repository into the same parent directory that holds Kaiju, but you may clone it anywhere you wish.

The tests can then be run with:

gradle -PKAIJU_AUTOCATS_DIR=path/to/autocats/dir test

where of course the correct path is provided to your cloned AUTOCATS repository directory. If cloned to the same parent directory as Kaiju as recommended, the command would look like:

gradle -PKAIJU_AUTOCATS_DIR=../autocats test

The tests cannot be run without providing this path; if you do forget it, gradle will abort and give an error message about providing this path.

Kaiju has a dependency on JUnit 5 only for running tests. Gradle should automatically retrieve and use JUnit, but you may also download JUnit and manually place into lib/ directory of Kaiju if needed.

You will want to run the update command whenever you pull the latest Kaiju source code, to ensure they stay in sync.

First-Time “Headless” Gradle-based Installation

If you compiled and built your own Kaiju extension, you may alternately install the extension directly on the command line via use of gradle. Be sure to set GHIDRA_INSTALL_DIR as an environment variable first (if you built Kaiju too, then you should already have this defined), then run gradle as follows:

export GHIDRA_INSTALL_DIR=<Absolute path to Ghidra install dir>
gradle install

or if you are unsure if the environment variable is set,

gradle -PGHIDRA_INSTALL_DIR=<Absolute path to Ghidra install dir> install

Extension files should be copied automatically. Kaiju will be available for use after Ghidra is restarted.

NOTE: Be sure that Ghidra is NOT running before using gradle to install. We are aware of instances when the caching does not appear to update properly if installed while Ghidra is running, leading to some odd bugs. If this happens to you, simply exit Ghidra and try reinstalling again.

Consider Removing Your Old Installation First

It might be helpful to first completely remove any older install of Kaiju before updating to a newer release. We’ve seen some cases where older versions of Kaiju files get stuck in the cache and cause interesting bugs due to the conflicts. By removing the old install first, you’ll ensure a clean re-install and easy use.

The gradle build process now can auto-remove previous installs of Kaiju if you enable this feature. To enable the autoremove, add the “KAIJU_AUTO_REMOVE” property to your install command, such as (assuming the environment variable is probably set as in previous section):

gradle -PKAIJU_AUTO_REMOVE install

If you’d prefer to remove your old installation manually, perform a command like:

rm -rf $GHIDRA_INSTALL_DIR/Extensions/Ghidra/kaiju.zip $GHIDRA_INSTALL_DIR/Ghidra/Extensions/kaiju