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The [WDigest](https://technet.microsoft.com/pt-pt/library/cc778868\(v=ws.10\).aspx?f=255\&MSPPError=-2147217396) protocol, introduced with Windows XP, is designed for authentication via the HTTP Protocol and is **enabled by default on Windows XP through Windows 8.0 and Windows Server 2003 to Windows Server 2012**. This default setting results in **plain-text password storage in LSASS** (Local Security Authority Subsystem Service). An attacker can use Mimikatz to **extract these credentials** by executing:
To **toggle this feature off or on**, the _**UseLogonCredential**_ and _**Negotiate**_ registry keys within _**HKEY\_LOCAL\_MACHINE\System\CurrentControlSet\Control\SecurityProviders\WDigest**_ must be set to "1". If these keys are **absent or set to "0"**, WDigest is **disabled**:
Starting with **Windows 8.1**, Microsoft enhanced the security of LSA to **block unauthorized memory reads or code injections by untrusted processes**. This enhancement hinders the typical functioning of commands like `mimikatz.exe sekurlsa:logonpasswords`. To **enable this enhanced protection**, the _**RunAsPPL**_ value in _**HKEY\_LOCAL\_MACHINE\SYSTEM\CurrentControlSet\Control\LSA**_ should be adjusted to 1:
**Credential Guard**, a feature exclusive to **Windows 10 (Enterprise and Education editions)**, enhances the security of machine credentials using **Virtual Secure Mode (VSM)** and **Virtualization Based Security (VBS)**. It leverages CPU virtualization extensions to isolate key processes within a protected memory space, away from the main operating system's reach. This isolation ensures that even the kernel cannot access the memory in VSM, effectively safeguarding credentials from attacks like **pass-the-hash**. The **Local Security Authority (LSA)** operates within this secure environment as a trustlet, while the **LSASS** process in the main OS acts merely as a communicator with the VSM's LSA.
By default, **Credential Guard** is not active and requires manual activation within an organization. It's critical for enhancing security against tools like **Mimikatz**, which are hindered in their ability to extract credentials. However, vulnerabilities can still be exploited through the addition of custom **Security Support Providers (SSP)** to capture credentials in clear text during login attempts.
To verify **Credential Guard**'s activation status, the registry key _**LsaCfgFlags**_ under _**HKLM\System\CurrentControlSet\Control\LSA**_ can be inspected. A value of "**1**" indicates activation with **UEFI lock**, "**2**" without lock, and "**0**" denotes it is not enabled. This registry check, while a strong indicator, is not the sole step for enabling Credential Guard. Detailed guidance and a PowerShell script for enabling this feature are available online.
For a comprehensive understanding and instructions on enabling **Credential Guard** in Windows 10 and its automatic activation in compatible systems of **Windows 11 Enterprise and Education (version 22H2)**, visit [Microsoft's documentation](https://docs.microsoft.com/en-us/windows/security/identity-protection/credential-guard/credential-guard-manage).
Further details on implementing custom SSPs for credential capture are provided in [this guide](../active-directory-methodology/custom-ssp.md).
**Windows 8.1 and Windows Server 2012 R2** introduced several new security features, including the _**Restricted Admin mode for RDP**_. This mode was designed to enhance security by mitigating the risks associated with [**pass the hash**](https://blog.ahasayen.com/pass-the-hash/) attacks.
Traditionally, when connecting to a remote computer via RDP, your credentials are stored on the target machine. This poses a significant security risk, especially when using accounts with elevated privileges. However, with the introduction of _**Restricted Admin mode**_, this risk is substantially reduced.
When initiating an RDP connection using the command **mstsc.exe /RestrictedAdmin**, authentication to the remote computer is performed without storing your credentials on it. This approach ensures that, in the event of a malware infection or if a malicious user gains access to the remote server, your credentials are not compromised, as they are not stored on the server.
It's important to note that in **Restricted Admin mode**, attempts to access network resources from the RDP session will not use your personal credentials; instead, the **machine's identity** is used.
This feature marks a significant step forward in securing remote desktop connections and protecting sensitive information from being exposed in case of a security breach.
Windows secures **domain credentials** through the **Local Security Authority (LSA)**, supporting logon processes with security protocols like **Kerberos** and **NTLM**. A key feature of Windows is its capability to cache the **last ten domain logins** to ensure users can still access their computers even if the **domain controller is offline**—a boon for laptop users often away from their company's network.
The number of cached logins is adjustable via a specific **registry key or group policy**. To view or change this setting, the following command is utilized:
Access to these cached credentials is tightly controlled, with only the **SYSTEM** account having the necessary permissions to view them. Administrators needing to access this information must do so with SYSTEM user privileges. The credentials are stored at: `HKEY_LOCAL_MACHINE\SECURITY\Cache`
Membership in the **Protected Users group** introduces several security enhancements for users, ensuring higher levels of protection against credential theft and misuse:
* **Credential Delegation (CredSSP)**: Even if the Group Policy setting for **Allow delegating default credentials** is enabled, plain text credentials of Protected Users will not be cached.
* **Windows Digest**: Starting from **Windows 8.1 and Windows Server 2012 R2**, the system will not cache plain text credentials of Protected Users, regardless of the Windows Digest status.
* **NTLM**: The system will not cache Protected Users' plain text credentials or NT one-way functions (NTOWF).
* **Kerberos**: For Protected Users, Kerberos authentication will not generate **DES** or **RC4 keys**, nor will it cache plain text credentials or long-term keys beyond the initial Ticket-Granting Ticket (TGT) acquisition.
* **Offline Sign-In**: Protected Users will not have a cached verifier created at sign-in or unlock, meaning offline sign-in is not supported for these accounts.
These protections are activated the moment a user, who is a member of the **Protected Users group**, signs into the device. This ensures that critical security measures are in place to safeguard against various methods of credential compromise.
For more detailed information, consult the official [documentation](https://docs.microsoft.com/en-us/windows-server/security/credentials-protection-and-management/protected-users-security-group).
| Windows Server 2003 RTM | Windows Server 2003 SP1+ | <p>Windows Server 2012,<br>Windows Server 2008 R2,<br>Windows Server 2008</p> | Windows Server 2016 |
<summary><strong>Learn AWS hacking from zero to hero with</strong><ahref="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
* If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@carlospolopm**](https://twitter.com/hacktricks\_live)**.**
* **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
