The job is to buy and sell drugs for profit and not get caught by police.

Most villages has drug dealers - guys in black hoodies, who usually hide in some back yards, so they're not seen from roads. The villages are small and it's not a problem to locate them.
There are three dealers in Komsodrinsk. One of them dwells in the slums behind hotel and delivery service. The other is right behind the steel plant, near solid buildings. Third one is right next to the grocery store, behind a stack of barrels.
The 08.03.23 update made dealers' location in Komsodrinsk completely random, which makes drugs smuggling even more challenging.
They sell packaged drugs ready for consuming and buy bricks.

Komsodrinsk
Sells weed bag for 9400
Buys hash brick for 230000

Sells cocaine bag for 11000
Buys cocaine brick for 250000

Sells meth bag for 14500
Buys meth brick for 300000

Lupova
Sells weed bag for 7800
Buys hash brick for 90000

Magyarfalu
Sells weed bag for 9100
Buys hash brick for 95000

Novocherkuta
Sells cocanie bag for 10000
Buys cocaine brick for 140000

Saversk
Sells weed bag for 9200
Buys hash brick for 105000

Kolovy
Sells meth bag for 13000
Buys cocaine brick for 120000

Balarsk
Sells meth bag for 14000
Buys meth brick for 135000

Gonsk
Sells meth bag for 14000
Buys weed bag for 18000

The village of Oasis (not the forestry, but the actual village by the small lake, marked with a flag on the map) has the cartel's den. The leftmost shack is enterable and has a dude inside. He buys packaged bags and sells bricks.

He buys:
Weed bag: 11000
Cocaine bag: 15000
Meth bag: 19000
Hash brick: 55000
Cocaine brick: 75000
Meth brick: 95000

He sells:
Meth brick: 110000
Hash brick: 75000
Cocaine brick: 95000

They fine you for a great amount of money and confiscate drugs. This works if there are drugs in victinity of about 50 meters from them, so it's not hard to avoid unwanted attention. At least in current state of the game, when they don't patrol or something.
Some update added police partols to roads - whatch them out!
Important thing is that they never check your backpack. So you can always carry up to 10 bricks of goods with no worries.
Changed in 12.06.22 update. Now the cops check your backpack, so you'll have to find the way around them.