Technical Description

A vulnerability has been identified in PHP, which could be exploited by local attackers to bypass security restrictions. This issue is due to a race condition between the time that "open_basedir" access controls for a symbolic link are verified and the time the requested file is accessed by certain functions, which could be exploited by malicious users to gain unauthorized access to restricted files via a PHP script containing "symlink()", "mkdir()", "unlink()", and "fopen()" calls.

It is also possible to bypass "safe_mode" and "open_basedir" restrictions via a malicious path and a NULL byte before a ";" in a "session_save_path" argument, followed by an allowed path.

Affected Products

PHP versions 5.x
PHP versions 4.x

Solution

VUPEN Security is not aware of any vendor-supplied patch.

References

http://www.vupen.com/english/advisories/2006/3901
http://www.hardened-php.net/advisory_082006.132.html
http://securityreason.com/achievement_securityalert/43

Credits

Vulnerabilities reported by Stefan Esser and Maksymilian Arciemowicz

ChangeLog

2006-10-04 : Initial release
2007-02-06 : Updated Advisory

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