Custom ISOs are the perfect vehicle for malware. A malicious actor can easily slip keyloggers, rootkits, or cryptocurrency miners into the system directory. Because these are baked into the OS, standard antivirus tools may fail to detect them upon installation.
In 2021, an analysis of 15 “custom Windows 7” ISOs (including “Deep Blue” variants) found:
Are you trying to or set up a virtual machine ? Do you need help finding official, safe Windows 7 ISOs ?
"Deep Blue" is not an official Microsoft release but rather a of Windows 7. These versions often include: