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Date: Tue, 1 Mar 2011 13:21:46 +0100
From: Pierre Joye <pierre.php@...il.com>
To: Dan Rosenberg <dan.j.rosenberg@...il.com>
Cc: oss-security@...ts.openwall.com, 
	Helgi Þormar Þorbjörnsson <helgi@....net>
Subject: Re: CVE Request: PEAR Installer 1.9.1 <= - Symlink Attack

On Tue, Mar 1, 2011 at 1:19 PM, Dan Rosenberg <dan.j.rosenberg@...il.com> wrote:

> The easiest way is to just open the target with the O_NOFOLLOW flag to
> avoid following symlinks and abort on failure.  If you need to support
> systems that don't have this flag, then perhaps you could consider
> using an application-specific temporary directory instead of operating
> in the world-writable /tmp.

In php, hard to do. But that's something we should keep in mind, maybe
we can expose this flag somehow.

>>> Also, I don't see a reason why a hard link couldn't be used for exploitation
>>> instead.
>>
>> Hard link are not detectable (lstat), they are treated like normal files.
>>
>
> Sure they are - just open the file, fstat() it,

+from PHP script.


-- 
Pierre

@pierrejoye | http://blog.thepimp.net | http://www.libgd.org

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