Note to Hollywood celebrities – just because you can upload things to the cloud, doesn’t mean your brain should be among them.

Intimate photographs of stars caught in their birthday suits, has a number of them, including Sports Illustrated model Kate Upton, planning on filing suits. They’re the latest to find out the hard way that just because it’s up in the cloud doesn’t mean it can’t come raining back to Earth. Yep, even if it’s Apple’s (AAPL) iCloud.

One of the many high-profile breaches in recent years, it has a lot of flummoxed stars wondering what to do now. For its part, Apple says it’s actively investigating breaches in some iCloud accounts, but refused to detail which ones. For now, it’s pretty obvious these aren’t just “any” accounts. The breach seems targeted at more than a half-dozen top actresses, including Oscar winner Jennifer Lawrence, pop singer Rihanna, and reality-show star Kim Kardashian, among others.

Hackers apparently deliberately targeted stars’ iCloud accounts. That’s nothing new. Unearthing compromising pictures of celebrities is a rich game for hackers who succeed and can sell their photographs or just embarrass celebs across various media. What’s unusual in this case is that these high-tech thieves managed to break into Apple’s systems that are seen as fairly secure.

At first, such concerns were dismissed, even as anonymous posters on the online message board 4chan began sharing sexually explicit images of Lawrence, and soon, others. Normally celebrities dismiss or totally ignore such findings, insisting the photographs are doctored or faked. Nickelodeon actress Victoria Justice claimed just that, arguing in a series of Twitter messages that supposedly compromising photographs of her weren’t real. So too Olympic gymnast McKayla Maroney and pop singer Ariana Grande.

Still, actress Mary Elizabeth Winstead took to the same social media sites to slam hackers who apparently had landed on very real photographs. “To those of you looking at photos I took with my husband years ago in the privacy of our home,” she wrote on Twitter, “hope you feel great about yourselves.”

“Knowing those photos were deleted long ago,” Winstead continued, “I can only imagine the creepy effort that went into this. Feeling for everyone who got hacked.”

Experts are still trying to discern how hackers broke into these accounts – perhaps by guessing their e-mail addresses, then randomly answering a variety of security questions to re-set passwords. Another theory is that hackers compromised a single voyeur’s account – someone who had been collecting pictures of celebrity nudes. Regardless, the damage is done and now celebrities (and their agents) are the ones asking how it can be un-done.

In two words – not easily. But perhaps this latest online breach serves as a reminder that there are risks to uploading material anywhere on the web, so maybe best “not” to upload at least certain material. As one security watcher suggested to me, “if you don’t want to share it, don’t send it, to anyone or any service.”

That’s doubly so when it comes to compromising photographs or compromising financial data. Once up in the vast cloud, it’s just a matter of time before some hacker finds a way to bring it down. The more logical, if not time-consuming solution, is to back up all such material on a separate disk or hard drive that’s in your possession, and not a company’s possession. That’s not to say that all online backup services are compromised, but increasingly many are getting to be “compromisable.”

Another solution is to double-up passwords, or implement what some anti-hackers call “two-factor authentication,” in which the user verifies his or her identity through a series of questions and keywords that confirms their identity.

Sadly, all this comes too little, too late for Jennifer Lawrence…now painfully aware that electronic voyeurs’ hunger for “The Hunger Games” star in ways even she might not have imagined. Take it from Rihanna, who knows all too well, whatever happens in your life takes on a life of its own online – especially when you put it there and give your enemies the ammunition.