And because it is a simple text file, it can be created with a text editor and your normal disk-burning software. Solution Two: Create f, while creating your f file according to solution One will work for most of your users, it will fail for a small percentage who have issues with the autorun function in their particular installation of Windows. The batch file in the first solution makes no allowances for errors and will merely fail when an error is encountered. This is where a shell utility can save the day, because these third-party applications contain routines for handling common errors and will complete the autorun process even if an error is encountered. For this example, we'll use autorun. Exe, antenna which can be downloaded from. Tarma has made autorun. Exe freely available for both personal and commercial use, and there are no requirements for copyright notices, etc. Exe, you make a simple modification to the f file by replacing t with the.
Sometimes you may need to pass an argument to the program to be auto played: autorun openmyprogram. Ico, not a program, sending customers, salespeople, investors, and employees presentations, pdf files, and html documents requires a slight variation to the basic f file and the addition of a dos batch file to the cd root directory. The f file opens a batch file, which then opens the file using the default program designated for that file type. For example: autorun t m iconmyicon. Ico, and the t file reads: echo off @start @exit, there is a variation on this idea that takes advantage of the. ShellExecute command: autorun m icontraining. Ico, using the f file to auto play your burned CDs will prevent another headache for your users and increase the likelihood of reaching your target audience.
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Contrary to what you may have heard from the. Riaa, burning a cd-r or cd-rw is not an activity restricted only to music pirates. In many business situations, the burned cd is the best way to distribute information to a target audience. For communications involving PowerPoint presentations, html, pdf forms, Flash animations, or a number of other applications, the portable and durable cd has become a common delivery method. The compact disk drive auto play feature, common to most operating systems, is a good way to simplify user experience. Auto play is controlled by a simple text-only file called. While there are dozens of software utilities available that will help you create the file, all you really need is a text editor and some basic knowledge.
This How. Microsoft Windows, but other operating systems will read business the f file in a similar fashion. Solution One: Create f, the basic configuration of the f states the program to run when the cd is inserted in the drive and the icon to display when the disk is viewed by windows Explorer or other directory listing software. The text-only file, which resides in the root directory of the cd, should follow this pattern: autorun openmyprogram. Ico, the icon file should also reside in the root directory of the. Variations, often the program you want to run will not be located in the root directory of the. If that is the case you must include the path: autorun openfolder1folder1Amyfile.
This is because the local user's password hashes, stored in the sam file, are encrypted with the syskey, and the syskey value is not available to an offline attacker who does not possess the syskey passphrase/floppy. Accessing private key via password reset edit In Windows 2000, the user's rsa private key is not only stored in a truly encrypted form, but there is also a backup of the user's rsa private key that is more weakly protected. If an attacker gains physical access to the windows 2000 computer and resets a local user account's password, 7 the attacker can log in as that user (or recovery agent) and gain access to the rsa private key which can decrypt all files. This is because the backup of the user's rsa private key is encrypted with an lsa secret, which is accessible to any attacker who can elevate their login to localSystem (again, trivial given numerous tools on the Internet). In Windows xp and beyond, the user's rsa private key is backed up using an offline public key whose matching private key is stored in one of two places: the password reset disk (if Windows xp is not a member of a domain). This means that an attacker who 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 later, the user's rsa private key is encrypted using a hash of the user's ntlm password hash plus the user name use of a salted hash makes it extremely difficult to reverse the process and recover the private key without. Also, again, setting Syskey to mode 2 or 3 (Syskey typed in during bootup or stored on a floppy disk) will mitigate this attack, since the local user's password hash will be stored encrypted in the sam file. Other issues edit Once a user is logged on successfully, access to his own efs encrypted data requires no additional authentication, decryption happens transparently. Thus, any compromise of the user's password automatically leads to access to that data. Windows can store versions of user account passphrases with reversible encryption, though this is no longer default behaviour; it can also be configured to store (and will by default on the original version of Windows xp and lower) Lan Manager hashes of the local user. It also stores local user account passphrases as ntlm hashes, which can be fairly easily attacked using " rainbow tables " if the passwords are weak (Windows Vista and later versions don't allow weak passwords by default). To mitigate the threat of trivial brute-force attacks on local passphrases, older versions of Windows need to be configured (using the security settings portion of Group Policy) to never store lm hashes, and of course, to not enable autologon (which stores plaintext passphrases in the. Further, using local user account passphrases over 14 characters long prevents Windows from storing an lm hash in the sam and has the added benefit of making brute-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, but simply deleted (i.e.
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Into the backup file) in encrypted form, and are not decrypted during backup. Starting with Windows Vista, a user's private key can be adds stored on a smart card ; Data recovery Agent (DRA) keys 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. Decrypting files using the local Administrator account edit 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, so there is always someone who can decrypt encrypted files of the users. Any non-domain-joined Windows 2000 computer will be susceptible to unauthorized efs decryption by anyone who can take over the local Administrator account, which is trivial given many tools available freely on the Internet. 7 In Windows xp and later, there is no default local Data recovery Agent and no requirement to have one. Setting syskey to mode 2 or 3 (syskey typed in during bootup or stored on a floppy disk) will mitigate the risk of unauthorized decryption through the local Administrator account.
When encrypted files are moved within an ntfs volume, the files remain encrypted. However, there are a number of occasions in which the file could be decrypted without the user explicitly asking Windows to. Files and folders are decrypted before being copied to a volume formatted with another file system, like fat32. Finally, when encrypted files are copied over solutions the network using the smb/cifs protocol, the files are decrypted before they are sent over the network. The most significant way of preventing the decryption-on-copy is using backup applications that are aware of the "Raw" apis. Backup applications that have implemented these raw apis will simply copy the encrypted file stream and the efs alternative data stream as a single file. In other words, the files are "copied" (e.g.
as the file Encryption key, or fek. It uses a symmetric encryption algorithm because 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 key 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. 5 to decrypt the file, the efs component driver uses the private key that matches the efs digital certificate (used to encrypt the file) to decrypt the symmetric key 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 below ntfs, it 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 way that is analogous to the inheritance of file permissions in ntfs: if a folder is marked for encryption, then by default all files and subfolders that are created under the folder are also encrypted.
4, see also the list of cryptographic file systems. Contents, basic ideas edit, when an operating system is running on a system without file encryption, access to shredder files normally 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 way, for example, would be to remove the disk and put it in another computer 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 most widely accepted solution to this is to store the files encrypted on the physical media (disks, usb pen drives, tapes, cds and so 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 key cryptography and symmetric key cryptography to make decrypting the files extremely difficult 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 password attacks.
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The, encrypting File system efs ) on, microsoft, windows is a feature resume introduced in version.0. Ntfs 1 that provides filesystem-level encryption. The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the computer. Efs is available in all versions of Windows developed for business environments (see. Supported operating systems below) from, windows 2000 onwards. 2, by default, no files are encrypted, but encryption can be enabled by users on a per-file, per-directory, or per-drive basis. 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 any of them.