Date: Tue, 1 Mar 2011 10:24:48 +0000 From: Helgi Þormar Þorbjörnsson <helgith@...il.com> To: oss-security@...ts.openwall.com Cc: Dan Rosenberg <dan.j.rosenberg@...il.com>, Pierre Joye <pierre.php@...il.com> Subject: Re: CVE Request: PEAR Installer 1.9.1 <= - Symlink Attack Hi, On 1 Mar 2011, at 09:11, Pierre Joye wrote: > hi, > > 2011/2/28 Dan Rosenberg <dan.j.rosenberg@...il.com>: >> I'm not familiar with this code or any of the context surrounding this >> fix, but it appears to be an incomplete fix. Checking for existence >> of a symlink and then opening the resource leaves open a window during >> which a legitimate file can be replaced with a symlink. > > Not sure it is fixable, or maybe using a lock on the symbolic link > while fetching its target (to be tested to be sure that such locks > cannot be overridden from shell). I assume you are referring to the parts for REST.php in the patch in question? At a second look, that part could do with improvements; I wrote up a function which takes TOCTOU into consideration. I'll have that patch done by the end of the day. For other situations I am using tempnam() (via the System class) as those files are only temporary and were being extracted from compressed archives; The predictability of their end destination where the centre part of the reported security problem. - Helgi
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