This indicates an attack attempt against an Argument Injection vulnerability in PHP CGI.
The vulnerability is caused by an error when the vulnerable software handles a malicious request. It allows a remote attacker to execute arbitrary code via a crafted URI.
PHP before 5.3.12
PHP 5.4.x before 5.4.2
System Compromise: Remote attackers can gain control of vulnerable systems.
The vendor issued a fix (5.3.12, 5.4.2) for CVE-2012-1823. It was incomplete fix, does not fully correct the vulnerability [CVE-2012-2311].
The vendor has issued a fix (5.3.13, 5.4.3) for CVE-2012-2311.