There are a few methods that criminals can acquire zero-day malware:
1. They can buy it on the black market.
2. They can produce it themselves.
3. They can steal it from a legitimate company or individual.
4. They can discover it in the wild.
The most typical manner in which crooks acquire zero-day malware is by buying it on the black market. There are a number of black markets that offer zero-day malware, and the costs can vary depending on the demand and the sophistication of the malware.
Crooks can also produce zero-day malware themselves, although this is less typical. In order to do this, they would need to have a good understanding of computer security and exploits.
https://westpennjournal.com/?p=357 Another way that crooks can get zero-day malware is by stealing it from a genuine company or person. This can be done by hacking into a business's network and taking the malware, or by social engineering a company or individual into providing the malware.
Lastly, bad guys can discover zero-day malware in the wild. This typically takes place when a security researcher finds a brand-new vulnerability and composes an exploit for it. The researcher might then offer the exploit to a criminal group, or the exploit might be dripped online.