diff --git a/windows/security/information-protection/bitlocker/bitlocker-countermeasures.md b/windows/security/information-protection/bitlocker/bitlocker-countermeasures.md index f2dcd3f3f1..619291134f 100644 --- a/windows/security/information-protection/bitlocker/bitlocker-countermeasures.md +++ b/windows/security/information-protection/bitlocker/bitlocker-countermeasures.md @@ -50,7 +50,7 @@ Before Windows starts, you must rely on security features implemented as part of A trusted platform module (TPM) is a microchip designed to provide basic security-related functions, primarily involving encryption keys. On some platforms, TPM can alternatively be implemented as a part of secure firmware. -BitLocker binds encryption keys with the TPM to ensure that a computer has not been tampered with while the system was offline. +BitLocker binds encryption keys with the TPM to ensure that a computer hasn't been tampered with while the system was offline. For more info about TPM, see [Trusted Platform Module](/windows/device-security/tpm/trusted-platform-module-overview). ### UEFI and secure boot @@ -60,8 +60,8 @@ Unified Extensible Firmware Interface (UEFI) is a programmable boot environment The UEFI specification defines a firmware execution authentication process called [Secure Boot](../secure-the-windows-10-boot-process.md). Secure Boot blocks untrusted firmware and bootloaders (signed or unsigned) from being able to start on the system. -By default, BitLocker provides integrity protection for secure boot by utilizing the TPM PCR[7] measurement. -An unauthorized EFI firmware, EFI boot application, or bootloader cannot run and acquire the BitLocker key. +By default, BitLocker provides integrity protection for Secure Boot by utilizing the TPM PCR[7] measurement. +An unauthorized EFI firmware, EFI boot application, or bootloader can't run and acquire the BitLocker key. ### BitLocker and reset attacks @@ -87,10 +87,10 @@ This helps mitigate DMA and memory remanence attacks. On computers with a compatible TPM, operating system drives that are BitLocker-protected can be unlocked in four ways: -- **TPM-only.** Using TPM-only validation does not require any interaction with the user to unlock and provide access to the drive. If the TPM validation succeeds, the user sign-in experience is the same as a standard logon. If the TPM is missing, changed, or if BitLocker detects changes to the BIOS, UEFI code or configuration, the critical operating system startup files, or the boot configuration, BitLocker enters recovery mode, and the user must enter a recovery password to regain access to the data. This option is more convenient for sign-in but less secure than the other options which require an additional authentication factor. -- **TPM with startup key.** In addition to the protection that the TPM-only provides, part of the encryption key is stored on a USB flash drive, referred to as a startup key. Data on the encrypted volume cannot be accessed without the startup key. -- **TPM with PIN.** In addition to the protection that the TPM provides, BitLocker requires that the user enter a PIN. Data on the encrypted volume cannot be accessed without entering the PIN. TPMs also have [anti-hammering protection](/windows/security/hardware-protection/tpm/tpm-fundamentals#anti-hammering) that is designed to prevent brute force attacks that attempt to determine the PIN. -- **TPM with startup key and PIN.** In addition to the core component protection that the TPM-only provides, part of the encryption key is stored on a USB flash drive, and a PIN is required to authenticate the user to the TPM. This configuration provides multifactor authentication so that if the USB key is lost or stolen, it cannot be used for access to the drive, because the correct PIN is also required. +- **TPM-only.** Using TPM-only validation doesn't require any interaction with the user to unlock and provide access to the drive. If the TPM validation succeeds, the user sign-in experience is the same as a standard sign in. If the TPM is missing or changed or if BitLocker detects changes to the BIOS or UEFI code or configuration, critical operating system startup files, or the boot configuration, BitLocker enters recovery mode, and the user must enter a recovery password to regain access to the data. This option is more convenient for sign-in but less secure than the other options, which require an additional authentication factor. +- **TPM with startup key.** In addition to the protection that the TPM-only provides, part of the encryption key is stored on a USB flash drive, referred to as a startup key. Data on the encrypted volume can't be accessed without the startup key. +- **TPM with PIN.** In addition to the protection that the TPM provides, BitLocker requires that the user enter a PIN. Data on the encrypted volume can't be accessed without entering the PIN. TPMs also have [anti-hammering protection](/windows/security/hardware-protection/tpm/tpm-fundamentals#anti-hammering) that is designed to prevent brute force attacks that attempt to determine the PIN. +- **TPM with startup key and PIN.** In addition to the core component protection that the TPM-only provides, part of the encryption key is stored on a USB flash drive, and a PIN is required to authenticate the user to the TPM. This configuration provides multifactor authentication so that if the USB key is lost or stolen, it can't be used for access to the drive, because the correct PIN is also required. In the following group policy example, TPM + PIN is required to unlock an operating system drive: @@ -119,12 +119,12 @@ You can use the System Information desktop app (MSINFO32) to check if a device h If kernel DMA protection is *not* enabled, follow these steps to protect Thunderbolt™ 3-enabled ports: -1. Require a password for BIOS changes. -2. Intel Thunderbolt Security must be set to User Authorization in BIOS settings. Please refer to [Intel Thunderbolt™ 3 and Security on Microsoft Windows® 10 Operating System documentation](https://thunderbolttechnology.net/security/Thunderbolt%203%20and%20Security.pdf) +1. Require a password for BIOS changes +2. Intel Thunderbolt Security must be set to User Authorization in BIOS settings. Refer to [Intel Thunderbolt™ 3 and Security on Microsoft Windows® 10 Operating System documentation](https://thunderbolttechnology.net/security/Thunderbolt%203%20and%20Security.pdf) 3. Additional DMA security may be added by deploying policy (beginning with Windows 10 version 1607 or Windows 11): - MDM: [DataProtection/AllowDirectMemoryAccess](/windows/client-management/mdm/policy-csp-dataprotection#dataprotection-allowdirectmemoryaccess) policy - - Group Policy: [Disable new DMA devices when this computer is locked](./bitlocker-group-policy-settings.md#disable-new-dma-devices-when-this-computer-is-locked) (This setting is not configured by default.) + - Group Policy: [Disable new DMA devices when this computer is locked](./bitlocker-group-policy-settings.md#disable-new-dma-devices-when-this-computer-is-locked) (This setting isn't configured by default.) For Thunderbolt v1 and v2 (DisplayPort Connector), refer to the “Thunderbolt Mitigation” section in [KB 2516445](https://support.microsoft.com/help/2516445/blocking-the-sbp-2-driver-and-thunderbolt-controllers-to-reduce-1394-d). For SBP-2 and 1394 (a.k.a. Firewire), refer to the “SBP-2 Mitigation” section in [KB 2516445](https://support.microsoft.com/help/2516445/blocking-the-sbp-2-driver-and-thunderbolt-controllers-to-reduce-1394-d). @@ -135,8 +135,9 @@ This section covers countermeasures for specific types of attacks. ### Bootkits and rootkits -A physically present attacker might attempt to install a bootkit- or rootkit-like piece of software into the boot chain in an attempt to steal the BitLocker keys. -The TPM should observe this installation via PCR measurements, and the BitLocker key will not be released. +A physically-present attacker might attempt to install a bootkit or rootkit-like piece of software into the boot chain in an attempt to steal the BitLocker keys. +The TPM should observe this installation via PCR measurements, and the BitLocker key won't be released. + This is the default configuration. A BIOS password is recommended for defense-in-depth in case a BIOS exposes settings that may weaken the BitLocker security promise. @@ -148,7 +149,7 @@ Require TPM + PIN for anti-hammering protection. ### DMA attacks -See [Protecting Thunderbolt and other DMA ports](#protecting-thunderbolt-and-other-dma-ports) earlier in this topic. +See [Protecting Thunderbolt and other DMA ports](#protecting-thunderbolt-and-other-dma-ports) earlier in this article. ### Paging file, crash dump, and Hyberfil.sys attacks These files are secured on an encrypted volume by default when BitLocker is enabled on OS drives. @@ -165,9 +166,9 @@ The following sections cover mitigations for different types of attackers. ### Attacker without much skill or with limited physical access -Physical access may be limited by a form factor that does not expose buses and memory. +Physical access may be limited by a form factor that doesn't expose buses and memory. For example, there are no external DMA-capable ports, no exposed screws to open the chassis, and memory is soldered to the mainboard. -This attacker of opportunity does not use destructive methods or sophisticated forensics hardware/software. +This attacker of opportunity doesn't use destructive methods or sophisticated forensics hardware/software. Mitigation: - Pre-boot authentication set to TPM only (the default) diff --git a/windows/security/information-protection/bitlocker/bitlocker-device-encryption-overview-windows-10.md b/windows/security/information-protection/bitlocker/bitlocker-device-encryption-overview-windows-10.md index cb7a3d5253..c14b762488 100644 --- a/windows/security/information-protection/bitlocker/bitlocker-device-encryption-overview-windows-10.md +++ b/windows/security/information-protection/bitlocker/bitlocker-device-encryption-overview-windows-10.md @@ -99,18 +99,18 @@ Exercise caution when encrypting only used space on an existing volume on which ## Encrypted hard drive support SEDs have been available for years, but Microsoft couldn’t support their use with some earlier versions of Windows because the drives lacked important key management features. Microsoft worked with storage vendors to improve the hardware capabilities, and now BitLocker supports the next generation of SEDs, which are called encrypted hard drives. -Encrypted hard drives provide onboard cryptographic capabilities to encrypt data on drives, which improves both drive and system performance by offloading cryptographic calculations from the PC’s processor to the drive itself and rapidly encrypting the drive by using dedicated, purpose-built hardware. If you plan to use whole-drive encryption with Windows 11 or Windows 10, Microsoft recommends that you investigate hard drive manufacturers and models to determine whether any of their encrypted hard drives meet your security and budget requirements. +Encrypted hard drives provide onboard cryptographic capabilities to encrypt data on drives, which improves both drive and system performance by offloading cryptographic calculations from the PC’s processor to the drive itself and rapidly encrypting the drive by using dedicated, purpose-built hardware. If you plan to use, whole-drive encryption with Windows 11 or Windows 10, Microsoft recommends that you investigate hard drive manufacturers and models to determine whether any of their encrypted hard drives meet your security and budget requirements. For more information about encrypted hard drives, see [Encrypted Hard Drive](../encrypted-hard-drive.md). ## Preboot information protection An effective implementation of information protection, like most security controls, considers usability and security. Users typically prefer a simple security experience. In fact, the more transparent a security solution becomes, the more likely users are to conform to it. -It's crucial that organizations protect information on their PCs regardless of the state of the computer or the intent of users. This protection shouldn't be cumbersome to users. One undesirable and previously commonplace situation is when the user is prompted for input during preboot, and then again during Windows sign in. Challenging users for input more than once should be avoided. +It's crucial that organizations protect information on their PCs regardless of the state of the computer or the intent of users. This protection shouldn't be cumbersome to users. One undesirable and previously commonplace situation is when the user is prompted for input during preboot, and then again during Windows sign-in. Challenging users for input more than once should be avoided. Windows 11 and Windows 10 can enable a true SSO experience from the preboot environment on modern devices and in some cases even on older devices when robust information protection configurations are in place. The TPM in isolation is able to securely protect the BitLocker encryption key while it is at rest, and it can securely unlock the operating system drive. When the key is in use and thus in memory, a combination of hardware and Windows capabilities can secure the key and prevent unauthorized access through cold-boot attacks. Although other countermeasures like PIN-based unlock are available, they aren't as user-friendly; depending on the devices’ configuration they may not offer additional security when it comes to key protection. For more information, see [BitLocker Countermeasures](bitlocker-countermeasures.md). ## Manage passwords and PINs -When BitLocker is enabled on a system drive and the PC has a TPM, you can choose to require that users type a PIN before BitLocker will unlock the drive. Such a PIN requirement can prevent an attacker who has physical access to a PC from even getting to the Windows sign in, which makes it virtually impossible for the attacker to access or modify user data and system files. +When BitLocker is enabled on a system drive and the PC has a TPM, you can choose to require that users type a PIN before BitLocker will unlock the drive. Such a PIN requirement can prevent an attacker who has physical access to a PC from even getting to the Windows sign-in, which makes it virtually impossible for the attacker to access or modify user data and system files. Requiring a PIN at startup is a useful security feature because it acts as a second authentication factor (a second “something you know”). This configuration comes with some costs, however. One of the most significant is the need to change the PIN regularly. In enterprises that used BitLocker with Windows 7 and the Windows Vista operating system, users had to contact systems administrators to update their BitLocker PIN or password. This requirement not only increased management costs but made users less willing to change their BitLocker PIN or password regularly. Windows 11 and Windows 10 users can update their BitLocker PINs and passwords themselves, without administrator credentials. Not only will this feature reduce support costs, but it could improve security, too, because it encourages users to change their PINs and passwords more often. In addition, Modern Standby devices don't require a PIN for startup: They're designed to start infrequently and have other mitigations in place that further reduce the attack surface of the system.