PHP 7 comes with a new built-in caching engine called OPcache. With this caching engine, a 10x performance increase can be expected depending on your workload. What you won’t expect though, is that OPcache offers a new and stealthy way to inject malicious code even under hardened environments. As the title suggests, this talk will cover a new exploitation technique allowing attackers to obtain and operate hidden webshells given the right circumstances. We’ll talk about how the technique works, how OPcache works internally, as well as some tools that can be used to facilitate exploitation and incident response.