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Preface

As I wrote in a previous blog post, I had an engagement last year where my task was to exfiltrate data from a workstation on some sort of storage media. The twist in that task was Lumension Sanctuary Device Control, and the version was 4.3.2, but I am not sure how newer version work and this seems to be a more general problem with device control solution, for example with Symantec products.

But what is a device control solution? In short, they audit I/O device use and block the attempts to use unauthorized devices. This includes hardware such as USB, PS/2, FireWire, CD/DVD so basically every I/O port of a computer. In my opinion, these are pretty good things and they offer a better looking solution than de-soldering the I/O ports from the motherboards or hot-gluing them, but on the other hand, they can be bypassed.

Bypass

OK, so what is the problem? Well the way these device control solutions work is that they load a few kernel drivers to monitor the physical ports of the machine. However... when you boot up the protected computer in safe mode, depending on the device control solution software, some of these drivers are not loaded (or if you are lucky, none of those modules will be loaded...) and this opens up the possibility to exfiltrate data.

In theory, if you have admin (SYSTEM maybe?) privileges, you might as well try to unload the kernel drivers. Just do not forget, that these device control solutions also have a watchdog process, that checks the driver and automatically loads it back if it is unloaded, so look for that process and stop or suspend it first.

In my case with the Lumension Sanctuary Device Control, I have found that when I boot the Workstation protected by the device control software in Safe Mode where, software's key logger protection module is not running... so I was still unable to use a USB stick, or a storage media, but I could plug in a keyboard for example...hmmm :)

As some of you probably already figured it out, now it is possible to use a pre-programmed USB HID, for example a Teensy! : ) I know about three different project, that uses this trick like these two mentioned in a Hackaday post, or this one. Unfortunately, the site ob-security.info no longer seems to be available (well, at least it is no longer related to infosec :D ), but you can still find the blog post and the files with the Wayback Machine.

For the hardware part, the wiring of the Teensy and the SD card adaptor is the same as I showed in the post on Making a USB flash drive HW Trojan or in the Binary deployment with VBScript, PowerShell or .Net csc.exe compiler post, so I will not copy it here again.

I have to note here that there are other ways to bypass these device control solutions, like the method what Dr. Phil Polstra did with the USB Impersonator, which is basically looks for an authorized device VID/PID and then impersonates that devices with the VID/PID.

Mitigation

Most probably, you will not need safe mode for the users, so you can just disable it... I mean, it is not that easy, but luckily there is a great blog post on how to do that. BTW, the first page of the post is for Windows XP, but you are not using XP anymore, aren't you? ;)

Alternatively, as I mentioned at the beginning, you might as well use some physical countermeasure (de-soldering/hot-gluing ports). That shit is ugly, but it kinda works.

Conclusion

Next time you will face a device control solution, try out these tricks, maybe they will work, and if they do, well, that's a lot of fun. :)

But don't get me wrong, these device control solutions and similar countermeasures are a good thing and you should use something like this! I know that they make doing business a bit harder as you are not able to plugin whatever USB stick you want, but if you buy a pile of hardware encrypted flash drives, and only allow those to be plugged in, you are doing it right ;)

Related word

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Ever wanted to turn your AV console into an Incident Response & Threat Hunting machine? Rastrea2r (pronounced "rastreador" - hunter- in Spanish) is a multi-platform open source tool that allows incident responders and SOC analysts to triage suspect systems and hunt for Indicators of Compromise (IOCs) across thousands of endpoints in minutes. To parse and collect artifacts of interest from remote systems (including memory dumps), rastrea2r can execute sysinternal, system commands and other 3rd party tools across multiples endpoints, saving the output to a centralized share for automated or manual analysis. By using a client/server RESTful API, rastrea2r can also hunt for IOCs on disk and memory across multiple systems using YARA rules. As a command line tool, rastrea2r can be easily integrated within McAfee ePO, as well as other AV consoles and orchestration tools, allowing incident responders and SOC analysts to collect forensic evidence and hunt for IOCs without the need for an additional agent, with 'gusto' and style!

Dependencies

Python 2.7.x
git
bottle
requests
yara-python

Quickstart

Clone the project to your local directory (or download the zip file of the project)

$git clone https://github.com/rastrea2r/rastrea2r.git
$cd rastrea2r

All the dependencies necessary for the tool to run can be installed within a virtual environment via the provided makefile.

$make help
help                           - display this makefile's help information
venv                           - create a virtual environment for development
clean                          - clean all files using .gitignore rules
scrub                          - clean all files, even untracked files
test                           - run tests
test-verbose                   - run tests [verbosely]
check-coverage                 - perform test coverage checks
check-style                    - perform pep8 check
fix-style                      - perform check with autopep8 fixes
docs                           - generate project documentation
check-docs                     - quick check docs consistency
serve-docs                     - serve project html documentation
dist                           - create a wheel distribution package
dist-test                      - test a wheel distribution package
dist-upload                    - upload a wheel distribution package

Create a virtual environment with all dependencies

$make venv
//Upon successful creation of the virtualenvironment, enter the virtualenvironment as instructed, for ex:
$source /Users/ssbhat/.venvs/rastrea2r/bin/activate

Start the rastrea2r server by going to $PROJECT_HOME/src/rastrea2r/server folder

$cd src/rastrea2r/server/
$python rastrea2r_server_v0.3.py
Bottle v0.12.13 server starting up (using WSGIRefServer())...
Listening on http://0.0.0.0:8080/

Now execute the client program, depending on which platform you are trying to scan choose the target python script appropriately. Currently Windows, Linux and Mac platforms are supported.

$python rastrea2r_osx_v0.3.py -h
usage: rastrea2r_osx_v0.3.py [-h] [-v] {yara-disk,yara-mem,triage} ...

Rastrea2r RESTful remote Yara/Triage tool for Incident Responders

positional arguments:  {yara-disk,yara-mem,triage}

modes of operation
 yara-disk           Yara scan for file/directory objects on disk
 yara-mem            Yara scan for running processes in memory
 triage              Collect triage information from endpoint

optional arguments:
 -h, --help            show this help message and exit
 -v, --version         show program's version number and exit


Further more, the available options under each command can be viewed by executing the help option. i,e

$python rastrea2r_osx_v0.3.py yara-disk -h
usage: rastrea2r_osx_v0.3.py yara-disk [-h] [-s] path server rule

positional arguments:
path          File or directory path to scan
server        rastrea2r REST server
rule          Yara rule on REST server

optional arguments:
-h, --help    show this help message and exit
-s, --silent  Suppresses standard output

For ex, on a Mac or Unix system you would do:

$cd src/rastrea2r/osx/

$python rastrea2r_osx_v0.3.py yara-disk /opt http://127.0.0.1:8080/ test.yar

Executing rastrea2r on Windows

Apart from the libraries specified in requirements.txt, we need to install the following libraries
- PSutil for win64: https://github.com/giampaolo/psutil
- WMI for win32: https://pypi.python.org/pypi/WMI/
- Requests: pip install requests
Compiling rastrea2r
Make sure you have all the dependencies installed for the binary you are going to build on your Windows box. Then install:
- Pywin32: http://sourceforge.net/projects/pywin32/files/ ** Windows only
- Pyinstaller: https://github.com/pyinstaller/pyinstaller/wiki

Currently Supported functionality

yara-disk: Yara scan for file/directory objects on disk
yara-mem: Yara scan for running processes in memory
memdump: Acquires a memory dump from the endpoint ** Windows only
triage: Collects triage information from the endpoint ** Windows only

Notes
For memdump and triage modules, SMB shares must be set up in this specific way:

Binaries (sysinternals, batch files and others) must be located in a shared folder called TOOLS (read only)

\path-to-share-foldertools
Output is sent to a shared folder called DATA (write only)

\path-to-share-folderdata
For yara-mem and yara-disk scans, the yara rules must be in the same directory where the server is executed from.
The RESTful API server stores data received in a file called results.txt in the same directory.

Contributing to rastrea2r project
The Developer Documentation provides complete information on how to contribute to rastrea2r project

Demo videos on Youtube

Video 1: Incident Response / Triage with rastrea2r on the command line - https://youtu.be/uFIZxqWeSyQ
Video 2: Remote Yara scans with rastrea2r on the command line - https://youtu.be/cnY1yEslirw
Video 3: Using rastrea2r with McAfee ePO - Client Tasks & Execution - https://youtu.be/jB17uLtu45Y

Presentations

rastrea2r at BlackHat Arsenal 2016 (check PDF for documentation on usage and examples) https://www.blackhat.com/us-16/arsenal.html#rastrea2r
https://github.com/aboutsecurity/Talks-and-Presentations/blob/master/Ismael_Valenzuela-Hunting_for_IOCs_rastrea2r-BH_Arsenal_2016.pdf
Recording of talk on rastrea2r at the SANS Threat Hunting Summit 2016
https://www.youtube.com/watch?v=0PvBsL6KKfA&feature=youtu.be&a

Credits & References

To Robert Gresham Jr. (@rwgresham) and Ryan O'Connor (@_remixed) for their contributions to the Triage module. Thanks folks!
To Ricardo Dias for the idea of using a REST server and his great paper on how to use Python and Yara with McAfee ePO: http://www.sans.org/reading-room/whitepapers/forensics/intelligence-driven-incident-response-yara-35542

Download Rastrea2R

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"Odysseus is a tool designed for testing the security of web applications. Odysseus is a proxy server, which acts as a man-in-the-middle during an HTTP session. A typical HTTP proxy will relay packets to and from a client browser and a web server. Odysseus will intercept an HTTP session's data in either direction and give the user the ability to alter the data before transmission. For example, during a normal HTTP SSL connection a typical proxy will relay the session between the server and the client and allow the two end nodes to negotiate SSL. In contrast, when in intercept mode, Odysseus will pretend to be the server and negotiate two SSL sessions, one with the client browser and another with the web server." read more...

Download: http://www.bindshell.net/tools/odysseus

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