The exploit was a result of a use-after-free vulnerability in the PHP set_magic_quotes() function. An attacker could exploit this vulnerability by sending a crafted HTTP request to a server running a vulnerable version of PHP, which would allow them to execute arbitrary code on the server.
High-quality lists of "sink" functions (like proc_open or assert ) that can be abused for command injection on older PHP versions. Summary of Vulnerabilities CVE-2013-2110 quoted_printable_encode Heap Overflow CVE-2014-3515 SPL Component Use-After-Free CVE-2015-6834 unserialize() Use-After-Free php 5416 exploit github
Here are some relevant sources:
1. The Critical CGI Argument Injection (CVE-2012-1823 & CVE-2024-4577) The exploit was a result of a use-after-free