Angler EK is a named malware distribution ecosystem, commonly understood as an exploit kit. In practice, exploit kits are criminal toolsets that help attackers deliver malware to victims by steering browsers to hostile code and trying to exploit software weaknesses automatically.
This matters in cyber security because it sits in the delivery layer of an attack: before encryption, credential theft, or botnet infection, the victim has to be reached and compromised. Angler EK is a useful example of how ransomware and other payloads can depend on separate distribution infrastructure rather than a single attacker action. Defenders look for the usual signs of exploit-kit activity, such as compromised sites, malicious redirects, suspicious scripts, and attempts to exploit outdated browsers, plugins, or other client software. Patching, browser hardening, web filtering, and endpoint protection all reduce this risk.