Date: Sat, 25 Aug 2018 10:32:12 +1000 (AEST) From: Damien Miller <djm@...drot.org> To: oss-security@...ts.openwall.com cc: openssh-unix-dev@...drot.org Subject: Re: Re: About OpenSSH "user enumeration" / CVE-2018-15473 On Fri, 24 Aug 2018, Solar Designer wrote: > Hi Damien, > > Thank you for sharing these thoughts with the community. > > On Fri, Aug 24, 2018 at 10:58:20AM +1000, Damien Miller wrote: > > Finally, and perhaps most importantly: there's a fundamental tradeoff > > between attack surface and fixing this class of bug. As a concrete > > example, fixing this one added about 150 lines of code to our > > pre-authentication attack surface. In this case, we were willing to do > > this because we had confidence in the additional parsing, mostly because > > it's been reviewed several times and we've conducted a decent amount of > > fuzzing on it. But, given the choice between leaving a known account > > validity oracle or exposing something we don't trust, we'll choose the > > former every time. > > Can you summarize for us all (on these mailing lists) the commits > leading to OpenSSH 7.8 that deal with this issue and add "about 150 > lines of code", please? It's this one: > * sshd(8): avoid observable differences in request parsing that could > be used to determine whether a target user is valid. (Commit 74287f5df9) Note that there's no new code added, but delaying the checks means more code is exposed before the authentication handler bails out. -d
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.