Information
The .netrc file contains data for logging into a remote host for file transfers via FTP.
While the system administrator can establish secure permissions for users' .netrc files, the users can easily override these.
Rationale:
The .netrc file presents a significant security risk since it stores passwords in unencrypted form. Even if FTP is disabled, user accounts may have brought over .netrc files from other systems which could pose a risk to those systems.
If a .netrc file is required, and follows local site policy, it should have permissions of 600 or more restrictive.
Solution
Making global modifications to users' files without alerting the user community can result in unexpected outages and unhappy users. Therefore, it is recommended that a monitoring policy be established to report user .netrc files and determine the action to be taken in accordance with site policy.
The following script will remove .netrc files from interactive users' home directories
#!/bin/bash
awk -F: '($1!~/(halt|sync|shutdown|nfsnobody)/ && $7!~/^(/usr)?/sbin/nologin(/)?$/ && $7!~/(/usr)?/bin/false(/)?$/) { print $6 }' /etc/passwd | while read -r dir; do
if [ -d '$dir' ]; then
file='$dir/.netrc'
[ ! -h '$file' ] && [ -f '$file' ] && rm -f '$file'
fi
done
Additional Information:
While the complete removal of .netrc files is recommended, if any are required on the system secure permissions must be applied.