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3.9 Ensure 'MachineKey validation method - .Net 4.5' is configured - Default

Information

The machineKey element of the ASP.NET web.config specifies the algorithm and keys that ASP.NET will use for encryption. The Machine Key feature can be managed to specify hashing and encryption settings for application services such as view state, Forms authentication, membership and roles, and anonymous identification.

The following validation methods are available:

Advanced Encryption Standard (AES) is relatively easy to implement and requires little memory. AES has a key size of 128, 192, or 256 bits. This method uses the same private key to encrypt and decrypt data, whereas a public-key method must use a pair of keys

Message Digest 5 (MD5) is used for digital signing of applications. This method produces a 128-bit message digest, which is a compressed form of the original data

Secure Hash Algorithm (SHA1) is considered more secure than MD5 because it produces a 160-bit message digest

Triple Data Encryption Standard (TripleDES) is a minor variation of Data Encryption Standard (DES). It is three times slower than regular DES but can be more secure because it has a key size of 192 bits. If performance is not a primary consideration, consider using TripleDES

Secure Hash Algorithm (SHA-2) is a family of two similar hash functions, with different block sizes known as SHA-256 and SHA-512. They differ in the word size; SHAS-256 used 32-bit words and SHA-512 uses 64-bit words.

It is recommended that SHA-2 methods be configured for use at the global level.

Rationale:

SHA-2 is the strongest hashing algorithm supported by the validation property so it should be used as the validation method for the MachineKey in .Net 4.5.

Impact:

N/A

Solution

Machine key encryption can be set by using the UI, running appcmd.exe commands, by editing configuration files directly, or by writing WMI scripts. To set the Machine Key encryption at the global level using an appcmd.exe command:

%systemroot%\system32\inetsrv\appcmd set config /commit:WEBROOT /section:machineKey /validation:<validation method>

Note: When Appcmd.exe is used to configure the <machineKey> element at the global level in IIS, the /commit:WEBROOT switch must be included so that configuration changes are made to the root web.config file instead of ApplicationHost.config.

OR

Enter the following command in PowerShell to configure:

Set-WebConfigurationProperty -pspath 'MACHINE/WEBROOT' -filter 'system.web/machineKey' -name 'validation' -value '<validation method>'

Default Value:

The default Machine Key validation method is SHA256.

See Also

https://workbench.cisecurity.org/benchmarks/13949

Item Details

Category: ACCESS CONTROL, IDENTIFICATION AND AUTHENTICATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|AC-17(2), 800-53|IA-5, 800-53|IA-5(1), 800-53|SC-8, 800-53|SC-8(1), CSCv7|14.4

Plugin: Windows

Control ID: cd5a6e690fb62f2bbe66d2e77bb8e1513a4c675022aa1256ac7be0cab4d120f6