San Francisco (AFP) - A huge trove of evidently intercepted Snapchat images and videos were exposed online Friday, raising fears about what may be revealed in messages intended to vanish seconds after beng viewed.

In what was being referred to as "The Snappening," people who used a third-party program instead of the official Snapchat application had copies of supposedly transient missives squirreled away by hackers who began posting them online late Thursday.

About half of Snapchat users are reported to be 17 years old or younger, raising worries that sexy self-shot images they thought would disappear will be shared on the Internet in what would amount to child pornography.

Snapchat released a statement Friday saying the startup's servers were not breached, nor were they the source of the leaked images.

The San Francisco-based company maintained that "Snapchatters were victimized" due to the use of outside applications to send or receive "Snaps" in a practice prohibited under the startup's terms of service.

Outside applications being eyed as sources for purloined Snapchat pictures are designed to let users undermine the intent of the service by keeping copies of self-destructing pictures sent or received.

- Malicious apps -

Unsanctioned mobile applications that basically hack into Snapchat have apparently been gathering copies of messages for years, storing them at a computer or computers online.

Hackers boasted a 13 gigabyte library of imagery, according to a report at news website Business Insider.

"Anybody who saw all those third-party Snapchat hack apps in the App Store should have seen it coming," said Nico Sell, founder of encrypted mobile messaging service Wickr and an organizer of the DefCon gathering of hackers annually in Las Vegas.

"You could tell that those were semi-malicious apps."

That is among reasons Wickr blocks third-party apps from working with the service, and why its messages "see no other computer" than the one they are sent to, according to Sell.

Story continues

"Technically, it could have been solved," Sell said of The Snappening.

"It could also be solved by the ecosystem not letting those apps exist."

Users of anonymity focused online forum 4chan have been downloading the swiped Snapchat messages and are constructing a searchable online archive, Business Insider reported.

The boasted 13 gigabytes of files could equal about a billion low-resolution images, by some estimates.

Snapchat rocketed to popularity, especially among teens, after the initial app was released in September 2011. Created by then Stanford University students, the app allows the sending of messages that disappear shortly after being viewed.