csonnek on "[Plugin: Jetpack by WordPress.com] Jetpack "

Without more specifics into the problem, I really can't speak to whether or not it's common. Jetpack is a widely used plugin, but any hacks specific to the plugin are rare. I've been doing support for Jetpack over three years and I've not seen an incident of hacking that was solely due to Jetpack; most times it's a MySQL injection or other vulnerability in WordPress, whether in the software itself or by poor user security practices.

What version of Jetpack are you using? What version of WordPress? Have you deleted and reinstalled a fresh copy of Jetpack downloaded directly from our plugin page on WordPress.org? Have you tued on a default WordPress theme to rule out a theme vulnerability? Are all your other plugins up to date and have you tried tuing them all off? Have you changed your database, hosting, and user passwords after the first incident?

Since you mention it's been hard to target, have you tried a paid service like Sucuri or WordFence to pinpoint and remove bad code? I'd recommend that direction, then with that data on the vulnerability, you'll be able to reach out to the developer of the theme or plugin that was indeed open to that type of attack.

Let me know if you have any questions.