The only attacks I know of are low brow phishing, DoS and web site defacements.
North Korea can't even feed its own people or keep the lights on in 2/3rds of the country. But nobody suggests they're unsophisticated cyber actors; that would be a demonstrably silly statement. Meanwhile: people routinely travel in and out of Iran; if you're not an American, it remains a major tourist destination. They have trade relationships around the world. They're not a hermit kingdom. If they want a world-class "APT" team, or 15 of them, all they have to do is decide to have them. (I assume they decided that a long time ago).
If you think Iran is unsophisticated or has minimal capabilities, I'd suggest you just look at a map, and, for bonus points, a GDP ranking, and consider that whatever evidence you personally may have collected on Iran's capabilities, you're seeing what they've allowed you to see.
Myself, I wouldn't even pick a fight with Kiribati.
What's the difference between what they can do, and what the leading countries in cybersecurity (US, Israel) can do(offensively and defensively)?
Is there a significant difference?
The other big question is how much this stuff applies to defense. The US presumably has better defensive capabilities than Iran could hope to have, by far. But better enough to matter? Open question.