TITLE:
PHP Trailing Slash "open_basedir" Security Bypass

SECUNIA ADVISORY ID:
SA16971

VERIFY ADVISORY:
https://secunia.com/advisories/16971/

CRITICAL:
Not critical

IMPACT:
Security Bypass

WHERE:
Local system

SOFTWARE:
PHP 4.4.x
https://secunia.com/product/5768/
PHP 5.0.x
https://secunia.com/product/3919/

DESCRIPTION:
thorben has discovered a security issue in PHP, which can be
exploited by malicious, local users to access certain files outside
the "open_basedir" root.

The security issue is caused due to fopen wrappers not correctly
obeying the "open_basedir" directive, which is designed to restrict
PHP scripts in certain environments from accessing files outside the
defined prefix. This can be exploited to access files in directories
outside the "open_basedir" root as if a trailing slash on the
"open_basedir" value is not taken into account.

Example:
Files in the "/user/test11/" directory can be accessed with the
"open_basedir" root set to "/user/test1/", but not files in the
"/user/test2/" directory.

The security issue has been confirmed in version 4.4.0 and 5.0.5.
Other versions may also be affected.

SOLUTION:
Use the "open_basedir" prefix as if a trailing slash on the value is
ignored.

PROVIDED AND/OR DISCOVERED BY:
thorben

ORIGINAL ADVISORY:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=323585

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