EXCLUSIVE

A sizzling model had nude photos hacked from the iCloud ... and the perp gave her an ultimatum -- ante up some cash, or the world will see your naked body.

Madison Louch says she realized on Sept. 7 she was locked out of her iCloud. Later that day she got a call from a guy who bragged he hacked her account. He told her he was "notorious" for hacking into the accounts of celebs and posting their nude photos online.

Madison says the guy demanded $900 or else he'd "ruin her modeling career." He ordered her to deposit the money in a brown Trader Joe's bag in a planter located at a building on Fairfax Ave in Hollywood.

Madison freaked out and called the LAPD, which then planned a sting. Turns out a woman came to the location at the exact time, grabbed the bag and cops swarmed her.

The woman -- Jamie Munoz -- told cops she knew she was picking up money for someone who was threatening to post nude photos, but she says she wasn't part of the plot. She gave cops the name of the guy -- Nicholas Douglas from Vancouver.

Munoz ended up pleading guilty to attempted extortion and got 3 years probation and community service -- no jail.