In short, some coders need a backdoor for updating the malware. Why? Because the antivirus and security firewalls can detect the module and signature of the malicious files and flag them. Then hackers need to update the malware 2022. Or sometimes, the attacker needs to execute another malware to collect data for another purpose.
So, either the malware can load the update with access and execute it. Or it uses the loader malware module. You can see how loader bypass Windows Defender last update 2023.
Loader Malware 2023 is used at RAT remote access trojans, Stealer, Botnets, Ransomware, Keylogger, and exploits.
Also, some crypter malware add plugin features to bundle any malware features and encrypt them.
Briefly, the Loader needs to keep FUD (fully undetectable) for antiviruses. So the top Loader 2023 uses the Windows bugs, vulnerabilities, and Zero- exploits to remain FUD. Also, the file-less Loader operates via the backdoor.
But anyway, the attacker needs the FUD malware Crypter to make a FUD malware and upload it by Loader malware 2023. We suggest reading our post about how to make FUD RAT too.