Cheat Sheets

Security - No SSH User Equivalency

Description

There must be no direct user equivalency. To detect this we match all SSH keys of all users against all authorized_keys to find network wide user equivalency.

Check Script: security-no-ssh-user-equivalency.sh

#!/bin/bash

# solution: Remove reported keys from authorized_keys #

homes=$(/usr/bin/getent passwd |/bin/egrep -v "(false|nologin)$" | /usr/bin/cut -d : -f 6) keys= result= authorized_keys_files= for h in $homes; do if [ -d "$h/.ssh" ]; then keys="$keys $(find "$h/.ssh" -name "*.pub")" if [ -f "$h/.ssh/authorized_keys" ]; then authorized_keys_files="$authorized_keys_files $h/.ssh/authorized_keys" fi fi done

for k in $keys; do kvalue=$(cut -d " " -f 2 "$k") if grep -q "$kvalue" $authorized_keys_files; then result="$result $k" fi done

if [ "$result" == "" ]; then result_ok else result_warning "Keys with possible user equivalency:" $result fi
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