This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.
This signature detects attempts to exploit a buffer overflow vulnerability in PHP 5.4.
PHP is a general-purpose scripting language especially suited for web development which can be embedded into HTML.
PHP is prone to a buffer-overflow vulnerability because it fails to effectively bounds-check user-supplied input submitted to the 'apache_request_headers()' function before copying it to an insufficiently sized buffer.
An attacker can exploit this issue to execute arbitrary machine code in the context of the PHP process. Failed exploit attempts will likely crash the webserver, denying service to legitimate users.