Institute for Security and Open Methodologies – The Open Source Security Testing Methodology Manual

Crowdstrike – Essential Guide to Conducting a Cloud Security Assessment

PCI Data Security Standard – Penetration Testing Guidance

Open Web Application Security Project (OWASP) Top 10

Open Web Application Security Project (OWASP) – Testing Tools

Open Web Application Security Project (OWASP) – Free for Open Source Application Security Tools

Open Web Application Security Project (OWASP) – Testing Guide

FedRAMP – Penetration Test Guidance

ISACA – Physical Penetration Testing: The Most Overlooked Aspect of Security

SANS Offensive Operations Training and Resources