Nah, Iran doesn't operate Su-27s. Anyway, Asia? Can't think of any Flanker operators in Asia that need to procure parts in a dubious way. I suppose you should think about some of the African Flanker operators. I'm guessing some of them, still must be under UN arms embargos. But who knows maybe China or Vietnam thinks official way for parts is too expensive.
If they are MiG-29 parts instead of Su-27/29 it opens up more options in Asia, Iran yes, but also Myanmar for example.
Russia doesn't neccessarily want to smuggle things. But if you are a high ranking officer in charge of the spare part supply for Russian fighters, you haven't been paid for a couple of months, and nobody is checking up on you.... well why not let some inventory dissappear ;-)
But well, maybe it's not even clear that the parts are indeed from Russia, and butBelarus, Ukraine, or Kazackstan. Also the manufacturing company might just want to sell to dubious customers.
I think it is very common that anything that falls under weapons/arms is smuggled. Even terrorist-suspects are smuggledÂ