Into a private enterprise does not sign a contract and do not buy social security, such a company is reliable

No contract, no social security. Such a company is basically trying to use cheap labor, do not want to be responsible for the employees to society. It's like a person who wants to marry you but doesn't have a marriage license, do you think it's reliable?

Of course, there are labor contract laws and social security laws.

If you work in this business, you can rely on these 2 laws; to fight for your interests. Because the labor law states:

Article 82 If an employer fails to conclude a written labor contract with a worker for more than one month but less than one year from the date of employment, the employer shall pay the worker two times the monthly wages.

If an employer violates the provisions of this Law by not entering into an open-ended labor contract with a worker, the employer shall pay the worker two times the monthly wages from the date the open-ended labor contract should have been entered into.

The Social Security Law also has corresponding provisions:

Whether you can fight for your rights depends on your own ability.