Is it possible for a rogue code to insert a cron job?

[albatroz]

We recently discovered that a wordpress site was infected with malware and was sending SPAM
using a cronjob, so I was wondering how was this cronjob created if the CPanel password is encrypted.

 

[Jcats]

Has nothing to do with cPanel password, they don't need to log into cPanel to create the cronjob, it can all be done via command line, example

Use PHP to create, edit and delete crontab jobs?

 

[cPanelLauren]

The response by @Jcats is correct - these sorts of malware have been on an uptick recently which is a reminder that it is extremely important to ensure that your WordPress/CMS installations are up to date and secure Wordpress has some advice on this which might be helpful as well Hardening WordPress « WordPress Codex

Thanks!