The Veil-Framework
@HarmJ0y
@ChrisTruncer
@VeilFramework

Who Are We?
 Will Schroeder (@harmj0y)
 Former national research lab keyboard monkey
 Chris Truncer (@ChrisTruncer)
 Florida State Graduate – Go Noles!
 Veris group pentesters by day, offensive security
researchers by night
 And we’re hiring!

Overview
 The Initial Problem
 Public Reaction and Ethical Considerations
 The Veil-Framework
 Evading AV: Veil-Evasion
 Payload Delivery: Veil-Catapult
 Situation Awareness: Veil-
PowerView
 Demos Throughout

The Initial Problem
 Antivirus doesn’t catch malware but (sometimes)
catches pentesters

Our Initial Solution
 A way to get around antivirus as easily as
professional malware
 Don’t want to roll our own backdoor each time
 Find a way to execute existing shellcode in an
AV-evading way

The Veil-Framework
 A toolset aiming to bridge the gap between
pentesting and red teaming capabilities
 We started with Veil-Evasion, and began to
branch out to payload delivery and Powershell
exploitation
 Nothing revolutionary here, but want to bring
together existing techniques and incremental
research try to push things forward

Ethical Considerations
 The disclosure debate is not new…
 Pentesters are 5+ years behind the professional
malware community
 This is already a problem the bad guys have
solved

HD Moore’s Take
 “The strongest case for information disclosure is
when the benefit of releasing the information
outweighs the possible risks. In this case, like
many others, the bad guys already won.”
 https://community.rapid7.com/community/meta
sploit/blog/2009/02/23/the-best-defense-is-
information

Public Reaction
 “surely this will just result in 21 new signatures for all major
AVs and then we're back to square one?”
 “Isn't our entire field meant to be working towards
increasing security, rather than handing out fully
functioning weapons?”
 “The other point here is that anything that helps to expose
how in-effective AV really is at stopping even a minimally
sophisticated attacker is a good thing.”
 http://www.reddit.com/r/netsec/comments/1fc2xp/veil_a
_metasploit_payload_generator_for_bypassing/

Twitter Reaction

Twitter Reaction

Evading AV
Veil-Evasion

Veil-Evasion’s Approach
 Aggregation of various shellcode injection
techniques across multiple languages
 These have been known and documented in other
tools
 Focused on automation, usability, and
developing a true framework
 Some shellcodeless Meterpreter stagers and
“auxiliary” modules as well

Veil-Evasion Features
 Can use Metasploit-generated or custom
shellcode
 MSF payloads/options dynamically loaded
 In the process of porting msfvenom
 Third party tools can be easily integrated
 Hyperion, PEScrambler, BackDoor Factory, etc.
 Command line switches to allow scriptability

Native Compilation
Python: pyinstaller/py2exe
C#: mono for .NET
C: mingw32

Module Development
 Implement your own obfuscation methods!
 Lots of reusable functionality
 Shellcode generation is abstracted and can be
invoked as needed
 https://www.veil-framework.com/tutorial-veil-
payload-development/

Shellcode Injection
 Void pointer casting
 no guarantee the memory region is executable
 VirtualAlloc
 allocate memory as RWX, copy code in and create
a thread
 HeapAlloc
 create a heap object and manually allocate
memory

Pyinstaller and DEP
 Pyinstaller produced .exe’s are DEP enabled by
default
 this ruins some shellcode injection methods
 Luckily Pyinstaller is open source
 we can recompile to turn off DEP opt-in
 https://www.veil-evasion.com/dep-pyinstaller/

Pwnstaller
 A generator for obfuscated Pyinstaller loaders
 BSides Boston „14 – Pwnstaller 1.0
 Dynamically generates and compiles a new
Pyinstaller loader on the fly
 http://www.harmj0y.net/blog/python/pwnstaller-
1-0/

Payload Releases
#VDay

VDay
 Since 9/15/2013, we’ve release at least one new
payload on the 15th of every month
 32 currently published payloads
 20+ additional payloads have been developed
so far
 we’re going to be releasing for a while :)

Native Stagers
 Stage 1 Meterpreter loaders don’t have to be
implemented in shellcode
 Meterpreter stagers can be written in higher-level
languages
 https://github.com/rsmudge/metasploit-loader

Veil-Evasion Stagers
 The following are the stagers currently available
in the framework (as of 5/15/14):
Language Stager
Python meterpreter/rev_tcp
Python meterpreter/rev_http
Python meterpreter/rev_http_contained
Python meterpreter/rev_https
Python meterpreter/rev_https_contained

Veil-Evasion Stagers
Language Stager
C# meterpreter/rev_tcp
C# meterpreter/rev_http
C# meterpreter/rev_https
C meterpreter/rev_tcp
C meterpreter/rev_tcp_service
C meterpreter/rev_http
C meterpreter/rev_http_service

How Stagers Work
 1) a tcp connection is opened to the handler
 2) the handler sends back 4 bytes indicating the
.dll size, and then transfers the .dll
 3) the socket number for this tcp connection is
pushed into the edi register
 4) execution is passed to the .dll just like regular
shellcode (void * or VirtualAlloc)
 reverse_http stagers skip steps 2 and 3

Veil-Evasion Demo

Payload Delivery
Veil-Catapult

Veil-Catapult

Veil-Catapult
 After payload generation, our focus shifted to
delivery
 Features nice integration with Veil-Evasion for on-
the-fly payload generation
 Cleanup scripts generated for payload killing
and deletion
 Command line flags for every option
 https://www.veil-framework.com/catapult/

.EXE Delivery
 Users can invoke Veil-Evasion to generate a
payload, or specify an existing .exe
 Payloads are delivered in one of two ways:
 upload/execute using Impacket and pth-toolkit
 host/execute UNC path to the attacker’s box
 UNC invocation gets otherwise detectable .EXEs
right by some AVs (lol @MSE)

Standalone Payloads
 Powershell: shellcode injector, bye bye disk writes
 http://www.exploit-
monday.com/2011/10/exploiting-powershells-
features-not.html
 Barebones python: uploads a minimal python
installation to invoke shellcode (see: next slide)
 Sethc backdoor: issues a registry command to set
up the sticky-keys RDP backdoor

Barebones Python
 Uploads a minimal python .zip installation and
7zip binary
 Python environment unzipped, shellcode invoked
using “-c …”
 The only files that touch disk are trusted python
libraries and a python interpreter
 Gets right by some reputation filters and antivirus!
 https://www.veil-framework.com/barebones-
python-injection/

Veil-Catapult Demo

Situational Awareness
Veil-PowerView

Situational Awareness; redux
 Goal: Gain an understanding of an exploited
host/network to aid in deeper infiltration
 Old schoolz:
 net group /domain
 net group “domain admins” /domain
 net users /domain
 net user “jsmith” /domain
 net view //hostname
 netsess.exe
 custom tools utilizing WinAPI calls
 blah blah blah

Veil-PowerView
 A pure Powershell situational awareness tool
 https://www.veil-framework.com/veil-powerview/
 Arose partially because a client banned “net”
commands on domain machines
 annoying, but only a minor roadblock
 Otherwise initially inspired by Rob Fuller’s
netview.exe tool
 Wanted something a bit more flexible that also
didn’t drop a binary to disk
 Started to explore and expand functionality

Get-Net*
 Full-featured replacements for almost all “net *”
commands, utilizing Powershell AD hooks and
various API calls
 Get-NetUsers, Get-NetGroup, Get-NetServers,
Get-NetSessions, Get-NetLoggedon, etc.
 See README.md for complete list, and function
descriptions for usage options

Meta-Functions
 Invoke-Netview: full-featured netview.exe
replacement, plus more:
 hostlists, jitter/delay, check share access, etc.
 Invoke-ShareFinder: finds open shares on the
network and checks if you have read access
 Invoke-FindLocalAdminAccess: port of
local_admin_search_enum.rb Metaspoit module
 finds machines the current user has admin access to
 Invoke-FindVulnSystems: queries AD for
machines likely vulnerable to MS08-067

User Hunting
 Goal: find which domain machines specific users
are logged into
 Invoke-UserHunter: finds where target users or
group members are logged into on the
network, optionally checking if you have admin
access on targets with found users!
 Utilizes Get-NetSessions and Get-NetLoggedon
 Invoke-StealthUserHunter: extracts
user.HomeDirectories from AD, and runs
Get-NetSessions on file servers to hunt for targets
 Significantly less traffic than Invoke-UserHunter

Veil-PowerView Demo

Get the Veil-Framework
 Github: https://github.com/Veil-Framework/
 Read more: https://www.veil-framework.com
 Now in Kali: apt-get install veil

Questions?
 harmj0y@veil-framework.com
 @harmj0y
 chris@veil-framework.com
 @ChrisTruncer
 #veil on freenode
 forums at https://veil-framework.com/forums/