Obtaining a for security research or penetration testing requires caution, as official Microsoft support for Windows 7 ended in January 2020. Because Microsoft no longer provides "clean" legacy ISOs directly, researchers typically use one of three methods: building an intentionally vulnerable lab environment, using trial virtual machines, or manually unpatching a standard installation. Primary Sources for Vulnerable Lab Environments
Since Microsoft no longer hosts official Windows 7 downloads, you must rely on community archives: Internet Archive (Archive.org) vulnerable windows 7 iso
(search for "Windows 7 SP1 ISO"). Avoid "pre-activated" or "modded" versions from untrusted third-party sites, as these often contain actual malware intended to infect the host. Verification Obtaining a for security research or penetration testing