Quoting Pierre-Anthony Lemieux (2021-12-15 21:41:25) > On Wed, Dec 15, 2021 at 12:20 PM Anton Khirnov <an...@khirnov.net> wrote: > > > > Quoting Pierre-Anthony Lemieux (2021-12-15 01:17:26) > > > > > > > > Now the question is whether a malicious attacker can craft those two > > > > files to get access to anything they shouldn't. I suppose at the very > > > > least the attacker can get information that the user opened the file (by > > > > adding an asset on an attacker's server) but that will be a danger with > > > > any playlists allowing network resources and can be controlled with > > > > io_open(). Can you think of any other possible issues? > > > > > > > > > > Some security considerations: > > > > > > - a DDoS can conceivably occur if a malicious CPL+ASSETMAP is widely > > > distributed. Both an ASSETMAP and a CPL are required since (a) the CPL > > > does not contain paths/hyperlinks and (b) only those resources > > > referenced by the CPL are fetched using the ASSETMAP. > > > - the CPL uses XML, which has its own security considerations. For > > > example, XML parsing can result in entities being fetched over the > > > network, but this is disabled by default in libxml AFAIK. > > > > This is concerning. From a brief glance at libxml2, it seems that you > > need to pass XML_PARSE_NONET as the last parameter to xmlReadMemory() to > > actually disabling network fetching. > > But it is possible I'm misreading the code, so if you or anyone else > > understands this better then clarifications are welcome. > > I was referring to entity expansion and the loading of DTDs being > disabled by default -- see XML_PARSE_NOENT and XML_PARSE_DTDLOAD at > [1-2].
Okay then. If nobody has further comments, I will push your latest patch in a few days. -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
