File Specification for Efs Upload to Florida Dos

Feature in Microsoft Windows

The Encrypting File System (EFS) on Microsoft Windows is a feature introduced in version 3.0 of NTFS^[one] that provides filesystem-level encryption. The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the reckoner.

EFS is available in all versions of Windows except the domicile versions (run across Supported operating systems beneath) from Windows 2000 onwards.^[ii] By default, no files are encrypted, just encryption can be enabled by users on a per-file, per-directory, or per-drive footing. Some EFS settings can also be mandated via Group Policy in Windows domain environments.^[3]

Cryptographic file system implementations for other operating systems are available, but the Microsoft EFS is not compatible with whatever of them.^[4] Meet also the list of cryptographic file systems.

Bones ideas [edit]

When an operating organization is running on a system without file encryption, access to files usually goes through OS-controlled user authentication and access control lists. However, if an attacker gains physical access to the computer, this barrier can be easily circumvented. One mode, for example, would be to remove the disk and put it in another figurer with an OS installed that can read the filesystem; another, would be to simply reboot the computer from a boot CD containing an OS that is suitable for accessing the local filesystem.

The most widely accepted solution to this is to shop the files encrypted on the physical media (disks, USB pen drives, tapes, CDs then on).

In the Microsoft Windows family of operating systems EFS enables this measure, although on NTFS drives only, and does so using a combination of public central cryptography and symmetric key cryptography to make decrypting the files extremely hard without the correct key.

However, the cryptography keys for EFS are in practice protected by the user account password, and are therefore susceptible to most countersign attacks. In other words, the encryption of a file is only as strong as the password to unlock the decryption key.

Functioning [edit]

Functioning of Encrypting File System

EFS works by encrypting a file with a bulk symmetric primal, besides known every bit the File Encryption Key, or FEK. Information technology uses a symmetric encryption algorithm considering it takes less time to encrypt and decrypt large amounts of data than if an asymmetric key cipher is used. The symmetric encryption algorithm used will vary depending on the version and configuration of the operating system; see Algorithms used by Windows version below. The FEK (the symmetric central that is used to encrypt the file) is then encrypted with a public key that is associated with the user who encrypted the file, and this encrypted FEK is stored in the $EFS alternative data stream of the encrypted file.^[five] To decrypt the file, the EFS component driver uses the private primal that matches the EFS digital certificate (used to encrypt the file) to decrypt the symmetric primal that is stored in the $EFS stream. The EFS component driver then uses the symmetric key to decrypt the file. Because the encryption & decryption operations are performed at a layer beneath NTFS, information technology is transparent to the user and all their applications.

Folders whose contents are to be encrypted by the file system are marked with an encryption attribute. The EFS component driver treats this encryption attribute in a fashion that is analogous to the inheritance of file permissions in NTFS: if a folder is marked for encryption, and so by default all files and subfolders that are created under the binder are also encrypted. When encrypted files are moved within an NTFS book, the files remain encrypted. Withal, there are a number of occasions in which the file could exist decrypted without the user explicitly asking Windows to do so.

Files and folders are decrypted before being copied to a book formatted with another file organization, like FAT32. Finally, when encrypted files are copied over the network using the SMB/CIFS protocol, the files are decrypted before they are sent over the network.

The about significant fashion of preventing the decryption-on-re-create is using backup applications that are aware of the "Raw" APIs. Backup applications that have implemented these Raw APIs will but copy the encrypted file stream and the $EFS alternative data stream as a unmarried file. In other words, the files are "copied" (e.1000. into the backup file) in encrypted grade, and are non decrypted during backup.

Starting with Windows Vista, a user's private central tin exist stored on a smart card; Data Recovery Amanuensis (DRA) keys tin can also be stored on a smart card.^[6]

Security [edit]

Vulnerabilities [edit]

Two significant security vulnerabilities existed in Windows 2000 EFS, and have been variously targeted since.

In Windows 2000, the local administrator is the default Data Recovery Agent, capable of decrypting all files encrypted with EFS by any local user. EFS in Windows 2000 cannot function without a recovery agent, and then there is e'er someone who can decrypt encrypted files of the users. Any not-domain-joined Windows 2000 computer will be susceptible to unauthorized EFS decryption by anyone who can take over the local Administrator business relationship, which is trivial given many tools available freely on the Internet.^[seven]

In Windows XP and later, there is no default local Data Recovery Amanuensis and no requirement to accept i. Setting SYSKEY to mode two or 3 (syskey typed in during bootup or stored on a floppy disk) will mitigate the adventure of unauthorized decryption through the local Administrator account. This is because the local user'due south password hashes, stored in the SAM file, are encrypted with the Syskey, and the Syskey value is non available to an offline attacker who does non possess the Syskey passphrase/floppy.

Accessing individual key via countersign reset [edit]

In Windows 2000, the user's RSA individual key is not simply stored in a truly encrypted class, but in that location is besides a backup of the user's RSA private key that is more weakly protected. If an assaulter gains physical access to the Windows 2000 computer and resets a local user account'southward password,^[7] the assaulter tin log in as that user (or recovery agent) and proceeds access to the RSA individual key which can decrypt all files. This is because the fill-in of the user'southward RSA individual key is encrypted with an LSA secret, which is accessible to whatsoever attacker who can elevate their login to LocalSystem (again, trivial given numerous tools on the Net).

In Windows XP and beyond, the user's RSA private fundamental is backed upwards using an offline public key whose matching private key is stored in one of two places: the password reset deejay (if Windows XP is not a member of a domain) or in the Active Directory (if Windows XP is a fellow member of a domain). This ways that an attacker who tin can authenticate to Windows XP as LocalSystem still does not have access to a decryption key stored on the PC's hard drive.

In Windows 2000, XP or afterward, the user'southward RSA private key is encrypted using a hash of the user's NTLM countersign hash plus the user proper noun – use of a salted hash makes it extremely hard to reverse the process and recover the private central without knowing the user's passphrase. Also, once again, setting Syskey to way 2 or 3 (Syskey typed in during bootup or stored on a floppy disk) will mitigate this assault, since the local user's password hash will be stored encrypted in the SAM file.

Other problems [edit]

Once a user is logged on successfully, access to his ain EFS encrypted data requires no boosted authentication, decryption happens transparently. Thus, any compromise of the user's countersign automatically leads to access to that data. Windows tin store versions of user account passphrases with reversible encryption, though this is no longer default behaviour; it tin also exist configured to store (and volition by default on the original version of Windows XP and lower) Lan Managing director hashes of the local user account passphrases, which can be attacked and broken easily. It also stores local user account passphrases as NTLM hashes, which tin be fairly easily attacked using "rainbow tables" if the passwords are weak (Windows Vista and later versions don't permit weak passwords by default). To mitigate the threat of little creature-strength attacks on local passphrases, older versions of Windows need to be configured (using the Security Settings portion of Grouping Policy) to never store LM hashes, and of grade, to not enable Autologon (which stores plaintext passphrases in the registry). Further, using local user account passphrases over 14 characters long prevents Windows from storing an LM hash in the SAM – and has the added do good of making beast-force attacks against the NTLM hash harder.

When encrypting files with EFS – when converting plaintext files to encrypted files – the plaintext files are not wiped, just merely deleted (i.e. information blocks flagged as "not in use" in the filesystem). This means that, unless they for instance happen to be stored on an SSD with TRIM support, they tin exist easily recovered unless they are overwritten. To fully mitigate known, not-challenging technical attacks against EFS, encryption should be configured at the binder level (so that all temporary files like Word document backups which are created in these directories are also encrypted). When encrypting individual files, they should be copied to an encrypted folder or encrypted "in place", followed by deeply wiping the disk volume. The Windows Cipher utility can be used (with the /Due west option) to wipe free space including that which nonetheless contains deleted plaintext files; various tertiary-party utilities may work likewise.^[8]

Anyone who tin can gain Administrators access can overwrite, override or change the Data Recovery Agent configuration. This is a very serious outcome, since an assailant can for case hack the Administrator account (using third-political party tools), set whatever DRA certificate they want as the Data Recovery Amanuensis and await. This is sometimes referred to equally a two-stage attack, which is a significantly dissimilar scenario than the risk due to a lost or stolen PC, but which highlights the take a chance due to malicious insiders.

When the user encrypts files after the first stage of such an attack, the FEKs are automatically encrypted with the designated DRA'south public key. The attacker merely needs to access the computer once more as Administrator to gain total access to all those afterwards EFS-encrypted files. Even using Syskey manner 2 or iii does not protect against this attack, because the attacker could support the encrypted files offline, restore them elsewhere and use the DRA's private key to decrypt the files. If such a malicious insider tin can gain physical admission to the figurer, all security features are to be considered irrelevant, because they could besides install rootkits, software or fifty-fifty hardware keyloggers etc. on the computer – which is potentially much more interesting and effective than overwriting DRA policy.

Recovery [edit]

Files encrypted with EFS can only be decrypted by using the RSA private key(s) matching the previously used public cardinal(southward). The stored copy of the user's private key is ultimately protected past the user's logon countersign. Accessing encrypted files from exterior Windows with other operating systems (Linux, for example) is not possible — not least of which because there is currently no third party EFS component commuter. Further, using special tools to reset the user'southward login password will return it impossible to decrypt the user's individual key and thus useless for gaining access to the user's encrypted files. The significance of this is occasionally lost on users, resulting in information loss if a user forgets his or her password, or fails to dorsum upwards the encryption key. This led to coining of the term "delayed recycle bin", to describe the seeming inevitability of data loss if an inexperienced user encrypts his or her files.

If EFS is configured to use keys issued past a Public Key Infrastructure and the PKI is configured to enable Key Archival and Recovery, encrypted files can be recovered by recovering the private cardinal first.

Keys [edit]

• user countersign (or smart card private key): used to generate a decryption central to decrypt the user'due south DPAPI Master Key
• DPAPI Master Central: used to decrypt the user's RSA individual key(s)
• RSA private key: used to decrypt each file's FEK
• File Encryption Key (FEK): used to decrypt/encrypt each file's data (in the primary NTFS stream)
• SYSKEY: used to encrypt the buried domain verifier and the password hashes stored in the SAM

Supported operating systems [edit]

Windows [edit]

• Windows 2000 Professional person, Server, Advanced Server and Datacenter editions
• Windows XP Professional, too in Tablet PC Edition, Media Heart Edition and x64 Edition
• Windows Server 2003 and Windows Server 2003 R2, in both x86 and x64 editions
• Windows Vista Business, Enterprise and Ultimate editions^[9]
• Windows 7 Professional person, Enterprise and Ultimate editions
• Windows Server 2008 and Windows Server 2008 R2
• Windows eight and 8.1 Pro and Enterprise editions
• Windows Server 2012 and Windows Server 2012 R2
• Windows 10 Pro, Enterprise, and Education editions.
• Windows Server 2016
• Windows Server 2019

Other operating systems [edit]

No other operating systems or file systems have native support for EFS.

New features available by Windows version [edit]

Windows XP

• Encryption of the Customer-Side Cache (Offline Files database)
• Protection of DPAPI Primary Key fill-in using domain-wide public cardinal
• Autoenrollment of user certificates (including EFS certificates)
• Multiple-user (shared) admission to encrypted files (on a file-past-file basis) and revocation checking on certificates used when sharing encrypted files
• Encrypted files tin can be shown in an culling colour (green by default)
• No requirement for mandatory Recovery Amanuensis
• Warning when files may be getting silently decrypted when moving to an unsupported file organisation
• Password reset disk
• EFS over WebDAV and remote encryption for servers delegated in Active Directory

Windows XP SP1

• Back up for and default use of AES-256 symmetric encryption algorithm for all EFS-encrypted files

Windows XP SP2 + KB 912761

• Preclude enrollment of self-signed EFS certificates

Windows Server 2003

• Digital Identity Management Service
• Enforcement of RSAKeyLength setting for enforcing a minimum key length when enrolling cocky-signed EFS certificates

Windows Vista^[x] and Windows Server 2008^{[11] [12]}

• Per-user encryption of Client-Side Cache (Offline Files)
• Support for storing (user or DRA) RSA individual keys on a PC/SC smart bill of fare
• EFS Re-Primal Magician
• EFS Key backup prompts
• Back up for deriving DPAPI Master Key from PC/SC smart card
• Support for encryption of pagefile.sys
• Protection of EFS-related secrets using BitLocker (Enterprise or Ultimate edition of Windows Vista)^{[thirteen] [xiv]}
• Group Policy controls to enforce
  • Encryption of Documents binder
  • Offline files encryption
  • Indexing of encrypted files
  • Requiring smart card for EFS
  • Creating a caching-capable user key from smart menu
  • Displaying a cardinal backup notification when a user key is created or inverse
  • Specifying the certificate template used for enrolling EFS certificates automatically

Windows Server 2008^[12]

• EFS self-signed certificates enrolled on the Windows Server 2008 server volition default to 2048-scrap RSA fundamental length
• All EFS templates (user and information recovery agent certificates) default to 2048-chip RSA key length

Windows 7 and Windows Server 2008 R2^[15]

• Elliptic-curve cryptographic algorithms (ECC). Windows 7 supports a mixed mode performance of ECC and RSA algorithms for backward compatibility
• EFS cocky-signed certificates, when using ECC, volition utilise 256-bit key past default.
• EFS can be configured to use 1K/2k/4k/8k/16k-bit keys when using self-signed RSA certificates, or 256/384/521-bit keys when using ECC certificates.

Windows ten version 1607 and Windows Server 2016

• Add EFS support on Fatty and exFAT.^[16]

Algorithms used by Windows version [edit]

Windows EFS supports a range of symmetric encryption algorithms, depending on the version of Windows in use when the files are encrypted:

Operating system	Default algorithm	Other algorithms
Windows 2000	DESX	(none)
Windows XP RTM	DESX	Triple DES
Windows XP SP1	AES	Triple DES, DESX
Windows Server 2003	AES	Triple DES, DESX[17]
Windows Vista	AES	Triple DES, DESX
Windows Server 2008	AES	Triple DES, DESX (?)
Windows 7 Windows Server 2008 R2	Mixed (AES, SHA, and ECC)	Triple DES, DESX

See also [edit]

• BitLocker
• Data Protection API
• Disk encryption
• Deejay encryption software
• eCryptfs
• EncFS
• Filesystem-level encryption
• Hardware-based full disk encryption

References [edit]

1. ^ "File Encryption (Windows)". Microsoft. Retrieved 2010-01-xi .
2. ^ EFS is bachelor on Windows 2000 Server and Workstation, on Windows XP Professional person, on Windows Server 2003 and 2008, and on Windows Vista and Windows 7 Business, Enterprise and Ultimate.
   EFS is not bachelor on Windows XP Abode Edition, nor on the Starter, Bones, and Home Premium editions of Windows Vista and Windows 7. It could not be implemented in the Windows 9x series of operating systems, since they did non natively support NTFS, which is the foundation for EFS.
3. ^ "Encrypting File System". Microsoft. 1 May 2008. Retrieved 24 August 2011.
4. ^ "Cryptographic Filesystems, Part 1: Design and Implementation". Security Focus. Retrieved 2010-01-11 .
5. ^ "Encrypting File Organization".
6. ^ Chris Corio (May 2006). "Starting time Wait: New Security Features in Windows Vista". TechNet Magazine. Microsoft. Archived from the original on 2006-11-10. Retrieved 2006-11-06 .
7. ^ ^{a b} ntpasswd, available since 1997 Archived Feb 12, 2016, at the Wayback Auto
8. ^ "The Encrypting File System". technet.microsoft.com.
9. ^ "Windows - Official Site for Microsoft Windows x Home & Pro OS, laptops, PCs, tablets & more". www.microsoft.com. Archived from the original on 2007-02-03. Retrieved 2008-01-20 .
10. ^ Kim Mikkelsen (2006-09-05). "Windows Vista Session 31: Rights Management Services and Encrypting File System" (PDF). presentation. Microsoft. Retrieved 2007-x-02 . ^{[ dead link ]}
11. ^ "Encrypting File System". documentation. Microsoft. 2007-04-30. Archived from the original on 2014-01-twenty. Retrieved 2007-xi-06 .
12. ^ ^{a b} "Changes in Functionality from Windows Server 2003 with SP1 to Windows Server 2008: Encrypting File Arrangement". documentation. Microsoft. 2007-09-01. Archived from the original on 2008-03-25. Retrieved 2007-eleven-06 .
13. ^ Scott Field (June 2006). "Microsoft Windows Vista Security Enhancements" (DOC). whitepaper. Microsoft. Retrieved 2007-06-fourteen .
14. ^ Microsoft Corporation (2006-xi-30). "Data Advice Protocol". patent. Microsoft. Retrieved 2007-06-xiv .
15. ^ "Changes in EFS". Microsoft TechNet. Retrieved 2009-05-02 .
16. ^ "[MS-FSCC]: Appendix B: Product Behavior". Microsoft. 2017-09-fifteen. Retrieved 2017-ten-02 . Back up for FAT and EXFAT was added in Windows 10 v1607 operating system and Windows Server 2016 and subsequent.
17. ^ Muller, Randy (May 2006). "How IT Works: Encrypting File System". TechNet Mag. Microsoft. Retrieved 2009-05-22 .

Further reading [edit]

• "Implementing the Encrypting File System in Windows 2000". Windows 2000 Evaluated Configuration Administrators Guide. Microsoft. Retrieved 20 December 2014.
• Bragg, Roberta. "The Encrypting File Organization". TechNet. Microsoft.
• "Encrypting File Organization (Windows Server 2008, Windows Vista)". TechNet. Microsoft. February 25, 2009.
• "Encrypting File System in Windows XP and Windows Server 2003". TechNet. Microsoft. April 11, 2003.
• Network Associates Laboratories. "How to Use the Encrypting File System (Windows Server 2003, Windows XP Professional)". MSDN. Microsoft.
• "Using Encrypting File Organisation". Windows XP Resource Kit. Microsoft. November 3, 2005.
• "Encrypting File Organization". Windows 2000 Resource Kit. Microsoft.
• "How EFS Works". Windows 2000 Resource Kit. Microsoft.

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Source: https://en.wikipedia.org/wiki/Encrypting_File_System

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