oss-security February 2011 archive
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oss-security: Re: [oss-security] CVE Request: PEAR Installer 1.9

Re: [oss-security] CVE Request: PEAR Installer 1.9.1 <= - Symlink Attack

From: Dan Rosenberg <dan.j.rosenberg_at_nospam>
Date: Mon Feb 28 2011 - 19:40:36 GMT
To: oss-security@lists.openwall.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 Žormar Žorbjörnsson <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
>