Date: Thu, 3 Jul 2014 21:07:39 +0100 From: Marek Kroemeke <kroemeke@...il.com> To: oss-security@...ts.openwall.com Subject: Re: Varnish - no CVE == bug regression I doubt that CDNs like Akamai, Fastly(varnish?), Cloudflare(nginx?) etc.. would agree that the fact that a core part of their infrastructure could be DoSed by one of their users is not a security vulnerability, but I'm happy to be in minority regarding this view. To be clear - I think that asserts in varnish are great, they decrease the severity of the problem from something potentially very dangerous to "just a DoS", but don't we usually try to track these as well with CVEs ? regards, Marek On Thu, Jul 3, 2014 at 8:41 PM, Kurt Seifried <kseifried@...hat.com> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > > On 03/07/14 11:12 AM, Stefan Bühler wrote: > > On Thu, 3 Jul 2014 08:15:06 +0000 Sven Kieske > > <S.Kieske@...twald.de> wrote: > > > >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > >> > >> I'd agree with this. And I don't get the argument from > >> poul-henning kamp, what I understand is: "hey, we trust our > >> backend server" well, but your backend server can make you crash, > >> so you probably shouldn't trust it in the first place? > >> > >> you _never_ can trust input, so you have to validate it, either > >> way, at least enough to not crash or perform malicious actions. > >> > >> Am 03.07.2014 09:48, schrieb Kurt Seifried: > >>> So as I understand this: Varnish front end for web servers, the > >>> web servers can trigger varnish to restart. Are the back end > >>> servers supposed to be able to cause varnish to restart? > >>> > >>> I'm guessing not. Scenario: hosting env, or a website with a > >>> vuln, whatever, you can now cause the varnish front ends to > >>> restart constantly, effectively causing a permanent denial of > >>> service. > >>> > >>> That sounds CVE worthy. Or am I missing something? > > > > you should never trust *untrusted* input. your root shell usually > > trusts the input it gets... > > > > so the valgrind developers decided that they consider the backend > > webservers trusted, at least regarding the capability to cause a > > DoS. > > > > for the record - so does lighttpd (a backend can trigger OOM as > > lighty reads (nearly) as fast as possible from a backend, as > > backends often only handle one request at a time); we usually tell > > people to use X-sendfile instead of sending ISOs through php. > > That also sounds like it needs a CVE then. You should not be able to > trivially DoS stuff, especially OOM, things should protect themselves > from OOM'ing especially if they accept user controlled input from the > network. > > > just because you disagree with such decisions doesn't make it CVE > > worthy (missing or wrong documentation could). > > So to be clear your argument is that the http backends serviced by > Varnish are supposed to be able to shut down Varnish, not by using an > administrative channel/command but by executing a denial of service > against Varnish? And that this is intended behaviour and thus not a > security vulnerability? > > > in case you actually want to assign a CVE here, maybe we can get > > one for the bad openssl default cipherstring too? because for that > > it is really obvious that it is f*** wrong, but i think that none > > was assigned because upstream didn't agree with it. > > > > regards, Stefan > > > > - -- > Kurt Seifried -- Red Hat -- Product Security -- Cloud > PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQIcBAEBAgAGBQJTtbIDAAoJEBYNRVNeJnmT/mkQAMmXrwXn4+Y/hGUGMfp3anFo > 7NVLg+50up/BhuVQ5fOA/EYClDQZNWSg8PrQWvo8cxwCtJOsXVFEHmG+2f7xNKkv > rCN97rMVz448hoFSHq5qwtWcZw/V8/A13hlAclDA7f7p+/B57Pok7igOciGwLbJb > zGXeODwFnHlX+eOZgn/hDt0FzG5n1cCHrnK4NgIT/yLSYDI5O235/0g999ooDrn7 > FwiOFxdnjkveBkcGde6VJ4TlyqA9qoYJ2S4t/fkvM9j/vXvag+V0wwSdDkpZuFNZ > ycERIVWZW6hnr7aZ/G76Rie2E4LY8B0T9cJF9pTA7FkJWF2Yg8LbPHz5jSH1cQuZ > bOanZXE8bPLAdLHKU0JWbDPYDdhjEk8mgLbbskSmMxslmygw9Z5kceUoug2Y75Xs > LRcpOuv08b3QO3wJNV6Z8fbkOYcdeTJPRmNLYrWoPqJHx8jWZzaUq1d1T8YGqos/ > V1KiFzDKH8Yw+yjmYAe+8DXpiOUH90yMYC8d8ewsipDXNNVHhyVUTeV/bNYT+0Gn > MU0GGSd90eLCC+czkw/tgY/XHIE0ycLeWDgTBUYkfOZ4UjgscMF6R5jcuJGMP71L > ftBbGNXduNHLkXL3GFUII+fAWQpWn14usmZZTHsoecmOoBPUV9paRuGBtzPmz+xJ > vHDLLMP7/qSLN88zY2d0 > =7hmC > -----END PGP SIGNATURE----- >
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