# Cron, At, and Timed Execution

> Master Linux task scheduling. Explore cron jobs, the at daemon, and how attackers abuse scheduled tasks for stealthy persistence and privilege escalation.

Canonical: https://codelivly.com/rooms/cron-at-and-timed-execution
Last updated: 2026-07-04

| | |
|---|---|
| Level | Beginner |
| Category | Cybersecurity |
| Lessons | 3 |
| Estimated time | 30 min |
| XP | 200 |

Dive into the automation backbone of Linux. The Cron, At, and Timed Execution module breaks down how the OS schedules tasks and executes them in the background.

You will learn to read and write crontabs, understand the at daemon for one-off execution, and discover how attackers weaponize these scheduling mechanisms to maintain persistence, escalate privileges via writable scripts, and bypass interactive monitoring. By the end of this module, you will be able to audit scheduled tasks and detect malicious automation hiding in plain sight.

## Lessons

1. Crontab Syntax & The Cron Daemon (30 min)
2. Cron Hijacking & Path Hijacking (30 min)
3. Wildcard Injection & The `at` Daemon (30 min)

## Related

- [Learning path: Linux Fundamentals for Cybersecurity](https://codelivly.com/learning-paths/linux-fundamentals-for-cybersecurity)
- [All rooms](https://codelivly.com/rooms)