Everyone here knows that com and net are almost full. So we webmasters look out for other extensions. There are country specific extensions that are available but they are resttricted to their country members only.
However, Hosting providers are providing these domains, even big providers
without checking. Is it a big crime to buy such domains, since everyone is just offering them. Do you own such domains? please help me out quickly.
What is the risk?
It’s not a big crime to register such domains, however if you are discovered as not being eligible for the TLD the domain operator could take it away from you… without notice. Personally I wouldn’t chance it because you would be building your brand identity on what is effectively a ticking bomb.
Why should it be a crime to register domain with extension which belongs to another country?
It isn’t a crime (not in the sense of being an offence), however it violates the contract you sign with the domain registrar (the regulators of the ccTLD, not the place you bought it). It could be seen legally as committing fraud if your claiming to meet the requirements of living in the nation you don’t and it’s certainly reasonable grounds for you to lose what you paid for without notice and face losing ownership over the domain itself. If you purchase something that is intended ONLY for residents of a certain country from a different nation, your violating the terms of usage agreement and deserve all you get. 
Each particular ccTLD domain name registration process has own rules. Some of this domain name extensions welcome foreigners some not.
Any examples?
Extensions such as .ws, .me, & .in have no specific requirements and are open for all to register at this time.
Domains ending with .eu, .ca, and .us have specific requirements where one must give evidence of residency or a business presence within the country of the corresponding county code.
Recently all .cn domain names have been restricted to business entities within China.
Each cctld has the option to limit issuing domains to a specified criteria.
Here’s an example for French domains (.fr):
Most ccTLD’s have a restriction of some type I use 101domain.com to check for extensions requirements as they have every extension + their restrictions.
Technically it is ‘illegal’ in the sense of the contract. However, I know and have heard of several people doing it.
.FR and com.au. You should be the resident of the country + for com.au domain names you should have business id in this region
You can always grab expiring domains from name(.)com snapnames(.)com and plenty of other sites.
Simple search on these sites with keyword you might be interested is expiring will list all the domains that are about to expire or in auction.