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

[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.  Also, I don't
see a reason why a hard link couldn't be used for exploitation
instead.

-Dan

2011/2/28 Helgi Þormar Þorbjörnsson <helgi () php net>:
> The lack of symlink checks in the PEAR installer 1.9.1 <= while doing
> installation and upgrades, which initiate various system write
> operations, can cause privileged users unknowingly to overwrite
> critical system files.
>
> Further information can be found in this temporary advisory
> http://pear.php.net/advisory-20110228.txt and the
>
> Fixes can be found at http://news.php.net/php.pear.cvs/61264
>
> - Helgi