4 ms·

I'd be very surprised if that were the case. The impression I got from the article was that they were just changing the extension on video files so that they co

I'd be very surprised if that were the case. The impression I got from the article was that they were just changing the extension on video files so that they could be uploaded as PDFs. For it to be steganography would require the PDF of the video file to still be readable as a PDF, which is vastly more work and takes much more technical knowhow (and the ability to download a decryption program) than just renaming.

cooper12 11y ago
Looks like MediaWiki (the software behind WIkipedia) verifies that the MIME type matches the extension: "MediaWiki tries to detect the MIME type of the files you upload, and rejects the file if the file-extension does not match the mime type" (https://www.mediawiki.org/wiki/Manual:MIME_type_detection https://www.mediawiki.org/wiki/Manual:MIME_type_detection) However, MIME types can be spoofed... (http://security.stackexchange.com/questions/35933/how-can-i-spoof-the-mimetype-of-a-file-upload http://security.stackexchange.com/questions/35933/how-can-i-...)
hobs 11y ago
Depends on the file type, there are a few that ignore anything in certain areas and if you change the extension should just work. Pretty sure, with gifs and zip you can just combine them together with one append command and you are done.
- Kristine1975 11y ago
  ZIP can contain arbitrary data before the archive data itself. That's an intended feature that's used e.g. for self-extracting archives. They look like this on disk: +-----------+-------------+ | extractor | zip archive | +-----------+-------------+ The extractor, when run, simply opens itself as a ZIP archive and decompresses itself. So you could append the ZIP archive to an image file and then decompress the result without having to remove the image beforehand. But you cannot concatenate several ZIP archives and expect a working bigger archive.

cooper12 11y ago

Looks like MediaWiki (the software behind WIkipedia) verifies that the MIME type matches the extension: "MediaWiki tries to detect the MIME type of the files you upload, and rejects the file if the file-extension does not match the mime type" (https://www.mediawiki.org/wiki/Manual:MIME_type_detection https://www.mediawiki.org/wiki/Manual:MIME_type_detection) However, MIME types can be spoofed... (http://security.stackexchange.com/questions/35933/how-can-i-spoof-the-mimetype-of-a-file-upload http://security.stackexchange.com/questions/35933/how-can-i-...)

hobs 11y ago

Depends on the file type, there are a few that ignore anything in certain areas and if you change the extension should just work. Pretty sure, with gifs and zip you can just combine them together with one append command and you are done.

Kristine1975 11y ago
ZIP can contain arbitrary data before the archive data itself. That's an intended feature that's used e.g. for self-extracting archives. They look like this on disk: +-----------+-------------+ | extractor | zip archive | +-----------+-------------+ The extractor, when run, simply opens itself as a ZIP archive and decompresses itself. So you could append the ZIP archive to an image file and then decompress the result without having to remove the image beforehand. But you cannot concatenate several ZIP archives and expect a working bigger archive.