I hunt sys admins 2.0

“I Hunt Sys Admins”

(U) Will@harmj0y

Version 2.0

$ whoami● Security researcher and red teamer for the

Adaptive Threat Division of Veris Group

● Co-founder of the Veil-Framework and founder of Veil’s PowerTools

● Cons:o Shmoocon ‘14: AV Evasion with the Veil Frameworko Defcon ‘14: Veil-Pillage: Post-exploitation 2.0o Derbycon ‘14: Passing the Torch: Old School Red

Teaming, New School Tactics?

What this is● Ways to hunt for target users on Windows

domains

● Ya really, that’s it

● Will cover as many tools and technique for doing this as I have time for

● Setting the stage

● Existing toolso psloggedon.exe, netsess.exe, PVEFindADUser.exe,

netview.exe, Nmap, smbexec, Veil-Pillage

● Domain data sourceso homeDirectory, profilePath, event logs, email

headers, SPNs

● PowerShellzo Sidenote: PowerShell WinAPI accesso PowerView

tl;dr

Setting the Stage● This talk is from the “assume breach”

perspectiveo i.e. assume foothold/access to a Windows domain

machine

● I’m also going to assume you know (more or less) what users you’re targeting

● PowerShell methods are going to heavily rely on PowerViewo https://github.com/veil-framework/PowerTools

User Hunting: Lateral Spread● Most common:

o If you have a privileged account, or local admin account, you want to figure out where high value users are logged in

● Hunt -> pop box -> Mimikatz -> profit

● Knowing what users log in to what boxes from where can give you a better understanding of a network layout and implicit trust relationships

“I Hunt Domain Admins”

“I Hunt Domain Admins”

“I Hunt Domain Admins”

User Hunting: Post DA● Red teaming isn’t about access, it’s about

data and showing impact!

● Once you get privileged access (like domain admin) there are likely specific targets you might want to go after

● Think incident response teams, CEOs, the linux team, database admins, etc.

Does the CEO Care?

How About Now?

Where my sysadmins at?Finding your prey

Existing Tools● Several tools have been written that allow

you to figure out who’s logged in where

● I’ll cover what’s already out there, including the positives/negatives for each

● “Offensive in depth”o You always want multiple ways of achieving the

same objective

● Component of Microsoft’s Sysinternalso “...determines who is logged on by scanning the

keys under the HKEY_USERS key.”o “To determine who is logged onto a computer via

resource shares, PsLoggedOn uses the NetSessionEnum API.”

● Needs remote registry access to determine who’s logged ino i.e. admin privileges on a remote machine

http://technet.microsoft.com/en-us/sysinternals/bb897545.aspx

psloggedon.exe

psloggedon.exe

netsess.exe● Component of

http://www.joeware.net/freetools/

● Utilizes the NetSessionEnum API callo http://msdn.microsoft.com/en-us/library/windows/des

ktop/bb525382(v=vs.85).aspx

● Think a version of “net session” that works on remote machines!o great for targeting file servers :)o no admin privs needed!

netsess.exe

PVEFindADUser.exe● Tool released by corelanc0d3r in 2009

● “Helps you find where AD users are logged in”o Can also check who’s logged into specific machines

● But “...you also need to have admin access on the computers you are running the utility against.”

https://www.corelan.be/index.php/2009/07/12/free-tool-find-where-ad-users-are-logged-on-into/

PVEFindADUser.exe

netview.exe● Rob Fuller’s (@mubix) netview.exe project,

presented at Derbycon 2012, is a tool to “enumerate systems using WinAPI calls”

● Finds all machines on the network, enumerates shares, sessions, and logged in users for each hosto And now can check share access, highlight high

value users, and use a delay/jitter :)o and also, no admin privs needed!

https://github.com/mubix/netview

netview.exe

Nmap● If you have a valid domain account, or local

account valid for several machines, you can use smb-enum-sessions.nse

● Don’t need to have admin privileges!nmap -sU -sS --script smb-enum-sessions.nse --script-args 'smbuser=jasonf,smbpass=BusinessBusinessBusiness!' -p U:137,T:139 192.168.52.0/24

http://nmap.org/nsedoc/scripts/smb-enum-sessions.html

Nmap

Smbexec● Awesome post-exploitation framework built

on top of patched Samba binaries

● The enumeration/checkda module can check machines for domain admin processes/sessions on particular targets

● However:o requires local admin on the target machineo only can target domain admins

Veil-Pillage● Veil-Pillage is a post-exploitation framework

conceptually similiar to Smbexec

● The enumeration/domain/group_hunter and enumeration/host/user_hunter modules will do the same tasklist and qwinsta process to hunt for specific target groups

● However:o requires local admin on the target machineo but can target more than just domain admins

Domain Data Sources“It’s a feature”

Active Directory Sources● There are a few components of Active

Directory user objects that warrant interest

● homeDirectoryo path to a user’s auto-mounted home directory

● profilePatho path to a user’s roaming profile

● Why?o Enumerating remote sessions against common

network servers lots of people use gives an excellent mapping of what users are where

Event Logs● Sometimes you have DA, but need to target

specific users (think the IR team :)

● If you can query the event logs on a domain controller, you can extract:o logon type (interactive/network), account name,

source network address

● @sixdub rolled this into a PowerShell script, which has since been incorporated into PowerView, more on this later

http://sixdub.net/2014/11/offensive-event-parsing-bringing-home-trophies/

Email Headers● If you have access to someone’s email

(Mimikatz+OWA, etc.) internal headers can provide a wealth of information

● Search for any chains to/from target users, and examine headers for given email chains

● If the “X-Originating-IP” header is present, you can trace where a user sent a given email from

Service Principal Names● SPNs aren’t just for machines

● Registering a service to run on a machine under a particular user account will register that machine/service for that user in ADo Makes a great place to check for users, all with a

single AD query

● Scott Sutherland (@_nullbind) has a great article on this:o https://blog.netspi.com/faster-domain-escalation-usin

g-ldap/

Manual Checks● To find your targets:

o net user “Domain Admins” /domain

● To find your file servers:o AdFind.exe -f "samAccountType=805306368" attr

homeDirectory | findstr /c:"homeDirectory"

● To find where your targets are:o NetSess.exe \\FILESERVER

Wrapping in VBScript● You can wrap some of these tools in some

basic VB script to automate it all up

● Run tool, filter for target users, etc.

● But why use VBScript, when you have...

PowerShell“Microsoft’s Post-Exploitation Language”

-@obscuresec

PowerShellz● PowerShell has some awesome AD hooks

and has various ways to access the lower-level Windows API

● You can also access the lower-level Win32 API for interesting functions○ NetSessionEnum for user sessions○ NetWkstaUserEnum for logged on users

● Thanks @mattifestation for lots of ways to access the underlying API functions!

Enumerating Targets● PowerView has several functions that can

help you enumerate target users and hunt them down

● Finding targets:o Get-NetGroups *wildcard* will return groups

containing specific wildcard termso Get-UserProperties will extract all user property

fields often interesting field names!

o Invoke-UserFieldSearch will search particular user fields for wildcard terms

Invoke-UserHunter● Flexible function that:

o queries AD for hosts or takes a target listo queries AD for users of a target group, or takes a

list/single usero uses Win32 API calls to enumerate sessions

(NetSessionEnum) and logged in users (NetWkstaUserEnum), matching against the target user list

● Can also check to see if you have local admin access on targetso but no admin privs needed to get good info!

Invoke-UserHunter

Invoke-UserHunter

Invoke-UserView● Several times on engagements we found

ourselves rerunning Invoke-UserHunter in order to re-hunt for specific users

● This creates a lot of unnecessary noise

● Invoke-UserView will run the exact same functions/checks that Invoke-UserHunter does, but preserves all output for later processing

Invoke-UserView

Invoke-StealthUserHunter● Uses an old red teaming trick

1. Queries AD for all users and extracts all homeDirectory fields to identify likely domain file servers

2. Runs NetSessionEnum against each file server to enumerate remote sessions, matching against target user list

● Gets reasonable coverage with a lot less traffic than UserHuntero and again, no admin privs needed

Invoke-StealthUserHunter

Invoke-StealthUserHunter

Invoke-UserProcessHunter● Utilizes the newly christened Get-

NetProcesseso this function makes it easy to enumerate running

processes on remote machines

● You will need admin privileges on the machines you’re enumerating

● Invoke-UserProcessHunter wraps this all up into a weaponized form

Invoke-UserProcessHunter

Invoke-UserEventHunter● Sometimes you have DA, but need to target

specific users (think the IR team :)

● Domain controller event logs make it trivial to track down domain users, provided you have domain admin access

● Get-UserLogonEvents implements @sixdub’s work on offensive event parsingo Invoke-UserEventHunt rolls this all into a

weaponized form

Invoke-UserEventHunter

Demo(s)

Shameless Sidebar● Want to research cool stuff like this?● Want to work with 13 x OSCPs and 3 x

OSCEs?● Want to do some sweet red teaming?● Hit me up to join Veris Group’s Adaptive

Threat Division

Questions?● Contact me:

o @harmj0yo will [at] harmj0y.neto harmj0y in #veil and #armitage on Freenode

● Read more:o http://blog.harmj0y.neto https://www.veil-framework.com

● Get PowerView:o https://github.com/Veil-Framework/PowerTools