Cis Ubuntu1604 V200 6 2 10

CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 6.2.10

Profile

• Level: 1 - Server
• Level: 1 - Workstation
• Assessment Status: Automated

Description

While no .rhosts files are shipped by default, users can easily create them.

Rationale

This action is only meaningful if .rhosts support is permitted in the file /etc/pam.conf. Even though the .rhosts files are ineffective if support is disabled in /etc/pam.conf, they may have been brought over from other systems and could contain information useful to an attacker for those other systems.

Audit Procedure

Command Line

Run the following script and verify no lines are returned:

#!/bin/bash
awk -F: '($1!~/(root|halt|sync|shutdown)/ &&
$7!~/^(\/usr)?\/sbin\/nologin(\/)?\$/ && $7!~/(\/usr)?\/bin\/false(\/)?\$/) {
print $1 " " $6 }' /etc/passwd | while read -r user dir; do
  if [ -d "$dir" ]; then
    file="$dir/.rhosts"
    if [ ! -h "$file" ] && [ -f "$file" ]; then
      echo "User: \"$user\" file: \"$file\" exists"
    fi
  fi
done

Expected Result

No output should be returned.

Remediation

Command Line

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 .rhosts files and determine the action to be taken in accordance with site policy.

The following script will remove .rhosts files from interactive users' home directories:

#!/bin/bash
awk -F: '($1!~/(root|halt|sync|shutdown)/ &&
$7!~/^(\/usr)?\/sbin\/nologin(\/)?\$/ && $7!~/(\/usr)?\/bin\/false(\/)?\$/) {
print $6 }' /etc/passwd | while read -r dir; do
  if [ -d "$dir" ]; then
    file="$dir/.rhosts"
    [ ! -h "$file" ] && [ -f "$file" ] && rm -r "$file"
  fi
done

Default Value

N/A

References

N/A

CIS Controls