Stop 13 · Security Tools & AutomationTopics · 6/8

Automating Repetitive Security Tasks

In short

If you have done a task by hand three times, it is probably time to automate it. Saved minutes add up, and machines do not forget the boring Monday checks.

Applying an automation mindset broadly — anything done manually more than a few times is a candidate for scripting, freeing analyst time for higher-judgment investigation work.

The blob sips chai while a conveyor belt stamps and stacks envelopes by itself.

Think of it like this

The stamping conveyor belt

A clerk used to stamp every envelope by hand. Then the office set up a small conveyor that stamps and stacks them automatically. Now the clerk sips chai and only checks the odd one that jams. That is automation done right: humans handle exceptions.

Watch it happen

From chore to cron job

Spot

Write steps

Script

Schedule

Alert

1/5Notice the repeat: every morning someone checks if your site certificates expire soon.

The big ideas

What you need to know

Do the time maths

Ten minutes a day is about 60 hours a year. Weigh that against the time to build and maintain the script.

Alert on exceptions

A daily "all OK" email trains people to ignore it. Alert only when action is needed.

Log what ran

Write each run's result to a log with a timestamp, so you can prove the check happened.

Watch the watcher

If the job itself stops running, you need to know. A simple heartbeat check catches silent failures.

See it in code

Walk through the code

bash

1#!/usr/bin/env bash2# cert-check.sh: warn if any of OUR site certs expire within 14 days3for host in shop.example.com api.example.com; do4  if ! echo | openssl s_client -connect "$host:443" -servername "$host" 2>/dev/null \5      | openssl x509 -noout -checkend $((14*24*3600)) >/dev/null; then6    echo "$(date -I) WARNING: $host certificate expires within 14 days"7  fi8done9 10# crontab -e   (runs every day at 07:30)11# 30 7 * * * /home/you/cert-check.sh >> /home/you/cert-check.log 2>&1

1/4Loop over the domains your team owns.

A classic automation: a daily, read only check of your own certificates. It stays quiet unless a renewal is due soon.

Save yourself the pain

Common mistakes

Oops

Automating a process nobody understands yet.

Do this instead

Run it by hand and write the steps first. Automating confusion just makes confusion faster.

Oops

A cron job that fails silently for months.

Do this instead

Log every run and alert if the job stops reporting. Check the log the first few days.

Your mission

Schedule your first check

~30 min

Quick check

Which alerting style is best for an automated daily check?

Go deeper

1List 3 recurring manual tasks from your own practice work, ranked by automation priority.
2Automate the highest-priority one from your list.
3Learn to weigh automation effort against actual time saved before automating everything blindly.