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Message-ID: <20030330141507.GA12493@openwall.com> Date: Sun, 30 Mar 2003 18:15:07 +0400 From: Solar Designer <solar@...nwall.com> To: popa3d-users@...ts.openwall.com Subject: Re: virtual.c another question On Sun, Mar 30, 2003 at 07:42:35PM +0600, Boris Kovalenko wrote: > Solar Designer wrote: > >>>>Why to run other code if we already know that user is invalid? Why > >>>>lstat directory and try to open file for this "INVALID" user? > >>>> > >>>This is to reduce information leaks via timing. > > > >It's primarily whether a username corresponds to an existing mail > >account or not. > > > Hmm...You do not find it too difficult? No. > And may be there is security hole? I don't see one, besides this defense against timing analysis still being imperfect due to properties of libc and the kernel. > According to the code, we will check and read at least > VIRTUAL_HOME_PATH/IP/VIRTUAL_AUTH_PATH/INVALID (with default settings it > will be /vhome/ip/auth/INVALID). Yes. This is intentional. It has to try some path, or the timings would be different. > Someone may use this knowlege to compromise the whole system, How? > or I'm paranoid? Paranoia is fine, but yours appears to be broken so far. ;-) > >I'm afraid these discussions on programming topics are of no use to > >most popa3d-users subscribers. If anyone is annoyed by them, please > >let me know and I'll be bringing them off-list in the future. > > > I'm afraid too. But because I don't know your direct e-mail I need to > write to the list. Haven't you read the docs? Can't you read e-mail headers? -- /sd
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