The Red Hat Enterprise Linux operating system must be configured so that if the Trivial File Transfer Protocol (TFTP) server is required, the TFTP daemon is configured to operate in secure mode.

STIG ID: RHEL-07-040720  |  SRG: SRG-OS-000480-GPOS-00227 | Severity: medium |  CCI: CCI-000366

Vulnerability Discussion

Restricting TFTP to a specific directory prevents remote users from copying, transferring, or overwriting system files.

Check

Verify the TFTP daemon is configured to operate in secure mode.

Check to see if a TFTP server has been installed with the following commands:

# yum list installed tftp-server
tftp-server.x86_64 x.x-x.el7 rhel-7-server-rpms

If a TFTP server is not installed, this is Not Applicable.

If a TFTP server is installed, check for the server arguments with the following command:

# grep server_args /etc/xinetd.d/tftp
server_args = -s /var/lib/tftpboot

If the "server_args" line does not have a "-s" option and a subdirectory is not assigned, this is a finding.

Fix

Configure the TFTP daemon to operate in secure mode by adding the following line to "/etc/xinetd.d/tftp" (or modify the line to have the required value):

server_args = -s /var/lib/tftpboot
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