Date: Thu, 19 Oct 2017 21:14:27 -0500 From: Benjamin Kaduk <kaduk@mit.edu> To: "WhiteWinterWolf (Simon)" <freebsd.lists@whitewinterwolf.com> Cc: "Ronald F. Guilmette" <rfg@tristatelogic.com>, freebsd-security@freebsd.org Subject: Re: WPA2 bugz - One Man's Quick & Dirty Response Message-ID: <20171020021427.GH96685@kduck.kaduk.org> In-Reply-To: <d32c3470-0a30-52c0-dd62-a7a448af6c99@whitewinterwolf.com> References: <32999.1508299211@segfault.tristatelogic.com> <53010303-bd65-26a1-64b9-6eefa325ca46@whitewinterwolf.com> <20171018224344.GA96685@kduck.kaduk.org> <d32c3470-0a30-52c0-dd62-a7a448af6c99@whitewinterwolf.com>
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On Thu, Oct 19, 2017 at 03:07:57PM +0200, WhiteWinterWolf (Simon) wrote: > Hi Benjamin, > > Le 19/10/2017 à 00:43, Benjamin Kaduk a écrit : > >> NFS has no built-in encryption, it may be possible to tunnel it but this > >> is out-of-scope here (using a VPN and tunnel everything would be easier > >> than nitpicking and tunnel only the NFS data flow). > > > > This statement is either false or highly misleading. NFS (both v3 and v4) > > is an RPC protocol, and RPCSEC_GSS exists and can provide per-message > > confidentiality protection. It may be true that Kerberos is basically > > the only GSS-API mechanism implemented for RPCSEC_GSS, and the necessary > > Kerberos setup is far more painful to set up than it needs to be, > > but all modern NFS implementations support it. > > The support RPCSEC_GSS has been added in NFSv4, it was not available in > NFSv3. > > Try to find any mention of RPCSEC_GSS in NFSv3 RFC: > https://tools.ietf.org/html/rfc1813 > > NFSv4 RFC on the other side documents the addition of this feature in > the protocol: > https://tools.ietf.org/html/rfc3010 Right, NFSv4 built it in from the start whereas it had to be hacked onto NFSv3 > Don't confuse RPCSEC_GSS with AUTH_KERBEROS and AUTH_DES, which weren't > widely supported and protect only the authentication phase: in-transit > data was still left unprotected (and this is what we are talking about > with this KRACK issue). It seems that RFC 2623 aims to clarify their differences. (It only covers the single-DES kerberos enctypes, which are not particularly secure anymore; see RFC 6649.) > The NFSv3 protocol itself had no authentication whatsoever, full trust > was given to the client system, making it a blatant security hole in > most infrastructures. That's precisely one of the reasons why NFSv4 was > needed. Indeed, the design goals were from a different era (and before my time). > I don't know if they managed to make it easy to use or if an external > Kerberos server is required, but in the former case that would indeed be > a great choice for end-users (but, given it is not the default and seems > to be among the "advanced" options, I fear that setting-up Kerberos is > left as an exercise for the user). Alas, it is left that way all too often. Since we're on the topic, I'll link http://web.mit.edu/kerberos/krb5-latest/doc/admin/install.html and note that that is quite different from the Heimdal included in the FreeBSD base system. > > >> SMB has no widely compatible encryption: > >> > >> - Microsoft has built its own, proprietary encryption available and > >> compatible only with the latest Windows versions. > >> - Open source implementations rely on TLS, natively supported by some > >> client but requiring (AFAIK) `stunnel` server-side. > > > > I am not a SMB/CIFS expert, but (e.g.) > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670508 seems to > > indicate that "proprietary" is false, and does not give much support > > to the claim that it requires TLS. (I believe in-kernel TLS support > > had not landed by June, when Xenial was getting its fix.) > > Sorry, but Microsoft SMB extensions *are* proprietary extensions. > > I encourage your to read the following page which explains the > impressive work made by Samba people: > > https://www.samba.org/samba/docs/myths_about_samba.html > > And in particular the description of their "French cafe" technique: > > http://samba.org/ftp/tridge/misc/french_cafe.txt Fair enough, and thank you for the links. I don't do much with SMB, myself, so had to try to search while writing my previous mail. -Ben
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