Driver Buddy Reloaded Quickstart

Table of Contents

• Driver Buddy Reloaded Quickstart
  • Table of Contents
  • Installation
  • Quick Usage
  • Advanced Usage
  • About Driver Buddy Reloaded
  • Finding DispatchDeviceControl
  • Labelling WDM and WDF Structures
  • Finding and Decoding IOCTL Codes
  • Flagging Functions
  • Finding DeviceName
  • Dumping Pooltags
  • Known Caveats and Limitations
  • Credits and Acknowledgements

Installation

Copy the DriverBuddyReloaded folder and the DriverBuddyReloaded.py script file into the IDA plugins folder, for example:

• %APPDATA%\Hex-Rays\IDA Pro\plugins\
• C:\Program Files\IDA Pro 7.6\plugins\
• ~/.idapro/plugins/

If you use Python v. 3.x, run the idapyswitch.exe binary (located in IDA's folder) from an admin command prompt.

NOTE: IDA SDK > v.7.5 is required in order for this script to run.

Quick Usage

To use the auto-analysis feature:

1. Start IDA and load a Windows kernel driver.
2. Go to Edit -> Plugins -> Driver Buddy Reloaded or press CTRL+ALT+A to start the auto-analysis.
3. Check the "Output" window for the analysis results.
4. A <DRIVER_NAME>.sys-YYYY-MM-DD-TIME_STAMP-DriverBuddyReloaded_autoanalysis.txt file containing the analysis results, will be written under IDA's DB directory.

To decode an IOCTL:

1. Place the mouse cursor on the line containing a suspected IOCTL code.
2. Right-click and select Driver Buddy Reloaded -> Decode IOCTL; alternatively, press the CTRL+ALT+D shortcut.

To decode ALL IOCTLs within a function:

1. Place the mouse cursor on the first instruction of the function you believe to be the IOCTL dispatcher ( DispatchDeviceControl, DispatchInternalDeviceControl, Possible_DispatchDeviceControl_#)
2. Right-click and select Driver Buddy Reloaded -> Decode ALL IOCTLs in Function; alternatively, press the CTRL+ALT+F shortcut.
3. A DriverName.sys-2021-12-10-TIME_STAMP-IOCTLs.txt/DriverName.sys-2021-12-10-TIME_STAMP-IOCTLs.txt_dumb.txt file, containing all the decoded IOCTLs up to that moment, will be written under IDA's DB directory.

Advanced Usage

• The vulnerable_function_lists directory contains a lists of potentially dangerous/problematic functions, Windows APIs and opcodes; a brief description on why a specific function/API has been listed is provided. You can edit the custom list including driver's specific functions.

  Note: winapi_function_prefixes will partial match to start of function name (e.g. Zw will match ZwClose, ZwCommitComplete and so on) while winapi_functions will perform exact matches only.

• In find_opcodes.py, the find_opcode_data option will prevent Driver Buddy Reloaded to find opcodes in data sections. Switching it to True will print something along this line: Found jnz short loc_15862 in sub_15820 at 0x00015852 Usually, going at the showed address and re-defining the selection as code will bring the searched opcode back.

  Watch out: switching it to True, will generates more false positives!

About Driver Buddy Reloaded

Driver Buddy Reloaded is an IDA Pro Python plugin that helps automate some tedious Windows Kernel Drivers reverse engineering tasks. It has a number of handy features, such as:

• Identifying the type of the driver
• Locating DispatchDeviceControl / DispatchInternalDeviceControl functions
• Populating common structures for WDF and WDM drivers
  • Attempts to identify and label structures like the IRP and IO_STACK_LOCATION
  • Label calls to WDF functions that would normally be unlabeled
• Finding and decoding IOCTL codes
• Flagging functions prone to misuse
• Finding potential DeviceName
• Dumping Pooltags

Finding DispatchDeviceControl

The tool can automatically locate and identify the DispatchDeviceControl routine. This function is used to route all incoming DeviceIoControl codes to the specific driver function associated with that code. Automatically identifying this function makes finding the valid DeviceIoControl codes for each driver much quicker. Additionally, when investigating possible vulnerabilities in a driver due to a crash, knowing the location of this function helps narrow the focus to the specific function call associated with the crashing DeviceIoControl code.

When the analysis is successful some subs will be renamed as follow:

• DriverEntry: the original first driver-supplied routine that is called after a driver is loaded. It is responsible for initializing the driver.
• Real_Driver_Entry: usually the function where the execution from DriverEntry has been transferred to. It is usually where the DeviceName is initialized.
• DispatchDeviceControl/DispatchInternalDeviceControl: if the tool was able to recover the functions at some specific offsets, the functions will then be renamed with the appropriate name.
• Possible_DispatchDeviceControl_#: if the tool was not able to recover DispatchDeviceControl or DispatchInternalDeviceControl, it employs an experimental searching, following the execution flow, and checking for cases where the function is loading known IO_STACK_LOCATION & IRP addresses; indicating that the function could be the DispatchDeviceControl. As it is based on heuristic, it could return more than one result, and it is prone to false positives.

Labelling WDM and WDF Structures

Several driver structures are shared among all WDM/WDF drivers. The tool is able to automatically identify these structures, such as the IO_STACK_LOCATION, IRP, and DeviceObject structures and can help save time during the reverse engineering process and provide context to areas of the driver where these functions are in use.

Finding and Decoding IOCTL Codes

While reversing drivers, it is common to come across IOCTL codes as part of the analysis. These codes, when decoded, reveal useful information and may draw focus to specific parts of the driver where vulnerabilities are more likely to exist.

By right-clicking on a potential IOCTL code, a context menu option is presented (alternatively using the Ctrl+Alt+D shortcut when the cursor is on the line containing a suspected IOCTL code) and can be used to decode the value. This will print out a table with all decoded IOCTL codes. By right-clicking on a decoded IOCTL code, in the disassembly view, it's possible to mark it as invalid; this will leave any non-IOCTL comment intact.

If you right-click, alternatively using the Ctrl+Alt+F shortcut, on the first instruction of the function you believe to be the IOCTL dispatcher ( DispatchDeviceControl, DispatchInternalDeviceControl, Possible_DispatchDeviceControl_#) under the Driver Buddy Reloaded menu, a “Decode All” option appears, this attempt to decode all the IOCTL codes it can find in the function. This is a bit hacky but most of the time it can speed things up.

• A DriverName.sys-2021-12-10-TIME_STAMP-IOCTLs.txt/DriverName.sys-2021-12-10-TIME_STAMP-IOCTLs.txt_dumb.txt file, containing all the decoded IOCTLs up to that moment, will be written under IDA's DB directory.

Flagging Functions

Driver Buddy Reloaded has lists of C/C++ functions, opcodes and Windows APIs (defined in the vulnerable_function_lists directory) that are commonly vulnerable or that can facilitate buffer overflow conditions. All found instances are reported back during the auto-analysis and can help while looking for possible user-controlled code paths reaching sensitive functions.

Finding DeviceName

The tool automatically attempts to find the drivers registered device paths (DeviceName), if no paths can be found by looking at Unicode strings inside the binary, then the analyst can manually try to use Madiant’s FLOSS in an attempt to find obfuscated paths.

Dumping Pooltags

During the auto-analysis, the tool also dumps the Pooltags used by the binary in a format that works with pooltags.txt. The output can then be copy-pasted at the end of the file and later picked up by WinDbg.

• A DriverName.sys-2021-12-10-TIME_STAMP-pooltags.txt file, containing all the dumped Pooltags, will be written under IDA's DB directory.

Known Caveats and Limitations

• Only IOCTL values >= 0x10000 will be automatically decoded, thus to prevent an high number of false positives. Issue #15
• Experimental DispatchDeviceControl searching works only for x64 drivers
• Shortcuts are incompatible with F-Secure's win_driver_plugin
• Shortcuts are incompatible with findcrypt-yara
• In find_opcodes.py, the find_opcode_data option will prevent Driver Buddy Reloaded to find opcodes in data sections. Switching it to True will print something along this line: Found jnz short loc_15862 in sub_15820 at 0x00015852 Usually, going at the showed address and re-defining the selection as code will bring the searched opcode back. Watch out: It is prone to false positives!

Credits and Acknowledgements

• Created in 2021 by Paolo Stagno aka @Void_Sec:
  • Made it compatible with Python 3.x
  • Made it compatible with IDA 7.x
  • Updated C/C++ function and Windows APIs list
  • Various bug fixing
  • Various improvements
  • Integrated part of the functionalities presents in F-Secure's win_driver_plugin
• DriverBuddy was originally written by Braden Hollembaek and Adam Pond of NCC Group.
• Using Satoshi Tanda's IOCTL decoder.
• The WDF functions struct is based on Red Plait's work and was ported to IDA Python by Nicolas Guigo, later updated by Braden Hollembaek and Adam Pond.
• Using Sam Brown's F-Secure win_driver_plugin to retrieve device name and pool tags, specifically Alexander Pick fork.
• The original code for adding items to the right-click menu (and possibly some other random snippets) came from 'herrcore'.
• Prodly developed using PyCharm for Open Source development by JetBrains