Most GTA mods aren't malware. Some are. Malicious ones often fit patterns. We break those patterns down.
The pattern
A mod is posted on a low-moderation site. The package contains malware executables alongside the mod content. The user downloads and installs it, then unknowingly runs the malware.
Typically the malware takes the form of cryptominers, information stealers (cookies, browser passwords) or remote-access trojans.
Warning signs
Mod asks to be run as administrator. EXE files bundled outside of the game directory. Mod includes an obfuscated installer. Mod asks for suspicious permissions to run. The file size of the mod doesn't match what it's supposed to do.
Comments warning of antivirus flags - ignore them at your peril.
How to protect yourself
Only download from trusted sites. Scan all downloads with VirusTotal before opening them. If you're paranoid, mod under a separate Windows account. Back up before any install.