From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 47C8342324 for ; Fri, 17 Dec 2021 14:25:51 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id E93ED68AE80; Fri, 17 Dec 2021 16:25:48 +0200 (EET) Received: from mail0.khirnov.net (red.khirnov.net [176.97.15.12]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id D88CE68AE4E for ; Fri, 17 Dec 2021 16:25:42 +0200 (EET) Received: from localhost (localhost [IPv6:::1]) by mail0.khirnov.net (Postfix) with ESMTP id 6093B24017C for ; Fri, 17 Dec 2021 15:25:42 +0100 (CET) Received: from mail0.khirnov.net ([IPv6:::1]) by localhost (mail0.khirnov.net [IPv6:::1]) (amavisd-new, port 10024) with ESMTP id u5hXFVpbc1gp for ; Fri, 17 Dec 2021 15:25:41 +0100 (CET) Received: from lain.red.khirnov.net (lain.red.khirnov.net [IPv6:2001:67c:1138:4306::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "lain.red.khirnov.net", Issuer "smtp.khirnov.net SMTP CA" (verified OK)) by mail0.khirnov.net (Postfix) with ESMTPS id 1A94B240179 for ; Fri, 17 Dec 2021 15:25:41 +0100 (CET) Received: by lain.red.khirnov.net (Postfix, from userid 1000) id 2D42416008E; Fri, 17 Dec 2021 15:25:41 +0100 (CET) From: Anton Khirnov To: FFmpeg development discussions and patches In-Reply-To: References: <20211213054336.19783-1-pal@sandflow.com> <163947788654.13029.10298345109744593134@lain.red.khirnov.net> <163950889025.13443.18056291142265665105@lain.red.khirnov.net> <163959962513.13029.16441945709966296103@lain.red.khirnov.net> Mail-Followup-To: FFmpeg development discussions and patches Date: Fri, 17 Dec 2021 15:25:41 +0100 Message-ID: <163975114109.13029.10142418833883066194@lain.red.khirnov.net> User-Agent: alot/0.8.1 MIME-Version: 1.0 Subject: Re: [FFmpeg-devel] [PATCH v10 1/2] avformat/imf: Demuxer X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Quoting Pierre-Anthony Lemieux (2021-12-15 21:41:25) > On Wed, Dec 15, 2021 at 12:20 PM Anton Khirnov 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-request@ffmpeg.org with subject "unsubscribe".