IBM z/OS SSL encryption options for the TN3270 Telnet Server must be specified properly for each statement that defines a SECUREPORT or within the TELNETGLOBALS.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-223831	RACF-TN-000020	SV-223831r877398_rule		Medium

Description
During the SSL connection process a mutually acceptable encryption algorithm is selected by the server and client. This algorithm is used to encrypt the data that subsequently flows between the two. However, the level or strength of encryption can vary greatly. Certain configuration options can allow no encryption to be used and others can allow a relatively weak 40-bit algorithm to be used. Failure to properly enforce adequate encryption strength could result in the loss of data privacy. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174, SRG-OS-000396-GPOS-00176, SRG-OS-000478-GPOS-00223, SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188, SRG-OS-000425-GPOS-00189, SRG-OS-000426-GPOS-00190, SRG-OS-000478-GPOS-00223

Description

During the SSL connection process a mutually acceptable encryption algorithm is selected by the server and client. This algorithm is used to encrypt the data that subsequently flows between the two. However, the level or strength of encryption can vary greatly. Certain configuration options can allow no encryption to be used and others can allow a relatively weak 40-bit algorithm to be used. Failure to properly enforce adequate encryption strength could result in the loss of data privacy. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174, SRG-OS-000396-GPOS-00176, SRG-OS-000478-GPOS-00223, SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188, SRG-OS-000425-GPOS-00189, SRG-OS-000426-GPOS-00190, SRG-OS-000478-GPOS-00223

STIG	Date
IBM z/OS RACF Security Technical Implementation Guide	2023-06-13

Details

Check Text ( C-25504r515181_chk )
Refer to the Profile configuration file specified on the PROFILE DD statement in the TCPIP started task JCL. If the following items are in effect for the configuration specified in the TCP/IP Profile configuration file, this is not a finding. NOTE: If an INCLUDE statement is coded in the TCP/IP Profile configuration file, the data set specified on this statement must be checked for the following items as well. NOTE: FIPS 140-2 minimum encryption is the accepted level of encryption and will override this requirement if greater. The TELNETGLOBALS block that specifies an ENCRYPTION statement states one or more of the below cipher specifications. Each TELNETPARMS block that specifies the SECUREPORT statement, specifies an ENCRYPTION statement states one or more of the below cipher specifications. And the TELNETGLOBALS block does or does not specify an ENCRYPTION statement. Cipher Specifications SSL_3DES_SHA SSL_AES_256_SHA SSL_AES_128_SHA

Check Text ( C-25504r515181_chk )

Refer to the Profile configuration file specified on the PROFILE DD statement in the TCPIP started task JCL.

If the following items are in effect for the configuration specified in the TCP/IP Profile configuration file, this is not a finding.

NOTE: If an INCLUDE statement is coded in the TCP/IP Profile configuration file, the data set specified on this statement must be checked for the following items as well.

NOTE: FIPS 140-2 minimum encryption is the accepted level of encryption and will override this requirement if greater.

The TELNETGLOBALS block that specifies an ENCRYPTION statement states one or more of the below cipher specifications.

Each TELNETPARMS block that specifies the SECUREPORT statement, specifies an ENCRYPTION statement states one or more of the below cipher specifications. And the TELNETGLOBALS block does or does not specify an ENCRYPTION statement.

Cipher Specifications
SSL_3DES_SHA
SSL_AES_256_SHA
SSL_AES_128_SHA

Fix Text (F-25492r515182_fix)
Configure the SECUREPORT and TELNETPARMS ENCRYPTION statements and/or the TELNETGLOBALS statement in the PROFILE.TCPIP file to conform to the requirements specified below. The TELNETGLOBALS block may specify an ENCRYPTION statement that specifies one or more of the below cipher specifications. Each TELNETPARMS block that specifies the SECUREPORT statement, an ENCRYPTION statement is coded with one or more of the below cipher specifications. And the TELNETGLOBALS block does or does not specify an ENCRYPTION statement. To prevent the use of non FIPS 140-2 encryption, the TELNETGLOBALS block and/or each TELNETPARMS block that specifies an ENCRYPTION statement will specify one or more of the following cipher specifications: Cipher Specifications SSL_3DES_SHA SSL_AES_256_SHA SSL_AES_128_SHA Note: Always check for the minimum allowed in FIPS 140-2.

Fix Text (F-25492r515182_fix)

Configure the SECUREPORT and TELNETPARMS ENCRYPTION statements and/or the TELNETGLOBALS statement in the PROFILE.TCPIP file to conform to the requirements specified below.

The TELNETGLOBALS block may specify an ENCRYPTION statement that specifies one or more of the below cipher specifications.

Each TELNETPARMS block that specifies the SECUREPORT statement, an ENCRYPTION statement is coded with one or more of the below cipher specifications. And the TELNETGLOBALS block does or does not specify an ENCRYPTION statement.

To prevent the use of non FIPS 140-2 encryption, the TELNETGLOBALS block and/or each TELNETPARMS block that specifies an ENCRYPTION statement will specify one or more of the following cipher specifications:

Cipher Specifications
SSL_3DES_SHA
SSL_AES_256_SHA
SSL_AES_128_SHA

Note: Always check for the minimum allowed in FIPS 140-2.