Bug reveals 'deleted' Snapchat videos
Videos sent via smartphone app Snapchat - which should disappear after a few seconds - can be preserved with easy to find tools.
Snapchat has proved popular as it deletes sensitive or risque photos and videos after a short delay.
But tech news site Buzzfeed has found that videos sent to iPhones can be stored using a workaround.
Snapchat said such "reverse engineering" was always going to be possible.
Using a widely available file-browsing computer program Katie Notopoulos, a staff reporter at Buzzfeed, found that Snapchat and its Facebook equivalent Poke could be used to copy videos temporarily stored on handsets before the apps have been used to view them.
The ability to send video via Snapchat was introduced on 14 December.
When videos were loaded but not opened Ms Notopoulos discovered it was possible to get at and view these copies when users connected their iPhone to a computer and used a file browser to look through its internal memory.
If videos were not viewed, she found, they were stored in a folder called "tmp" by Snapchat or "mediacard" on Facebook's Poke. Copying the files in these folders to a hard drive stopped them being automatically deleted.
Snapchat is also available on Google Android phones. Ms Notopoulos did not try to find out if videos were preserved in the same way on such smartphones. However, earlier in December Snapchat did issue a patch for a bug that put permanent versions of unwatched videos into the media gallery on Android phones.
Snapchat founder Evan Spiegel told Ms Notopoulos that those who enjoyed the service the most would not go to such lengths to view videos.
"There will always be ways to reverse engineer technology products - but that spoils the fun!" he wrote.
Facebook later added that: "While Pokes disappear after they are read, there are still ways that people can potentially save them... because of this, people should think about what they are sending, and share responsibly."