The official Sesame Street YouTube channel was taken offline on Monday after the account was defaced and began sharing adult content. The defacement also extended to the Sesame Street profile, which was altered to read, "Who doesn't love porn kids? Right! Everyone loves it!"

The inappropriate videos were available for about 20 minutes, before the Sesame Street channel was taken offline for violations of YouTube's community guidelines, according to Graham Cluley, senior technology consultant at Sophos. He obtained screen grabs of the defacement and uploaded content, which he said was definitely not safe for work.

In the altered profile, the attackers listed themselves as being "Mredxwx and my partner Mrsuicider91." But the YouTube user with the handle Mredxwx uploaded a message to YouTube denying any involvement in the defacement. "I did not hack Sesame Street," he said. "I am an honest youtuber. I work hard to make quality gameplay videos and most important I respect the community guidelines."

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According to a statement released by Google, which owns the video-sharing website, "YouTube's Community Guidelines prohibit graphic content. As always, we remove inappropriate material as soon as we are made aware of it."

How did Sesame Street's YouTube channel get hacked? "We don't know exactly how it occurred but my hunch is that they were somehow careless with their password, so either the admin password they were using for that account was easy to guess, or more likely it was phished, meaning they were tricked into clicking a link and entering it," said Cluley, in an interview.

Sesame Workshop, the nonprofit organization behind Sesame Street, did not respond immediately to a request for comment about the attack.

Defacements of businesses' social media channels are nothing new. Earlier this year, for example, the Fox News Twitter feed was altered to claim that President Obama had been killed. Of course, that hack didn't involve a children's television property.

"It's particularly galling to everybody because it happened to Sesame Street, because it's an institution--they don't deserve something like this," said Cluley. "Not that anyone deserves something like this, but you'd think this is the last sort of place that anyone would want to attack"--not least because children looking at the YouTube channel may have seen entirely inappropriate material, he noted.

What can businesses do to prevent their YouTube channel from being hacked, and having to deal with the resulting brand-management cleanup? Start by using a unique password for every website, not least for corporate properties. "Something like 30% of people use the same password for everything, which means if your password is hacked in one place it can result in the compromise of all sorts of assets," said Cluley. Beyond stopping password reuse, also choose long, random passwords, to make them more difficult for attackers to guess or even deduce via brute-force or dictionary-driven attacks.

But unfortunately, simple passwords today appear to be the norm. According to an analysis conducted on the Sony user passwords leaked by the hacking group LulzSec, for example, 50% of passwords employ fewer than eight characters, and only 4% use more than three character types, meaning uppercase, lowercase, numbers, or non-alphanumeric characters.

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