Re: CVE Request: PEAR Installer 1.9.1 <= - Symlink Attack

[Pierre Joye <pierre.php () gmail com>]

hi,

2011/2/28 Dan Rosenberg <dan.j.rosenberg () gmail 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).

>  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.

Cheers,
-- 
Pierre

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