Can hostiles do anything to enter, attack through, or destroy the hut?

I don't think so. But a good dispel magic works.

Dang this thing is powerful!

I know this is an old thread but it's worth noting -- while it doesn't say here (aside from the implication of 'dome' and that it forms 'around and above,' not below, the caster), the PHB entry for the spell states explicitly that the shape is a hemisphere. The wording stresses foreign creatures and objects can't pass through the force dome itself, but does nothing to prevent something accessing the enclosed space from below.

Unlikely anyone's going to sit back and watch their enemies take a shovel to the ground outside their magic hut, but there are faster ways to move earth, and there are monsters that burrow.

is there any actual difference between this and leomund's tiny hut?

Nope, you'll find most of the spells with someones name in it have a generically named counterpart 

Jeremy Crawford said that means it has a floor. Search sage advice

Tiny Hut is a horrible designed spell, especially for 2nd level. Far too powerful as most enemies are not going to have Dispel Magic available to get rid of it. There is no reason why a 2nd level spell can create a unbreakable barrier for 8 hours. I've modified mine so that it has HP and is resistant to all damage. This lets a foe eventually break through it, but should allow a smart group to still use it.

And I see nothing in the description that would say it has a floor. Also, there isn't enough info to determine if the dome creates fresh air or not, so does it protect you from noxious gas? Again, poorly worded and just too powerful as written for its level. IMO

1. Not a 2nd, but a 3rd level spell. Puts it on par with dispel magic.
2. It's your house, but downgrading a spell is rarely satisfying to the players, especially if they give up one of the many great 3rd level spell options for this as a spell selection.
3. Several things in the description point to it being a complete enclosure and therefore having a floor:
   1. The range is a hemisphere (3D shape with round 'top' and flat 'bottom').
   2. Crawford posting on twitter that a hemisphere has a 'floor' (google it yourself).
   3. The word 'inside' is used, not 'under', a dome.
4. The atmosphere inside is impervious to outside elements, including natural and magical, and is comfortable (fresh/breathable air implied here).

1. even at third its still moronicly powerful
2. and poorly designed stuff shouldn't be allowed to remain hence it gets fixed.
3. Nothing in Hemisphere is inherently hollow. also, it says nothing about generating air, nor cleaning it. Comfortable and dry does not equal sanitizing. Also a dome is not a hemisphere, so they shouldn't use two different terms that don't  mean the same thing.
4. Again, it merely states comfortable and dry, not impervious to outside elements. 

We could argue semantics forever, but given the casting time, this is designed as a rest spell. A DM can easily overcome the effects of this spell, no matter how you interpret it. There are much more glaring power differences than this spell. Smoking the players out or using move earth to go under are obscure counters sure to anger your players. 2 simple counters are to use dispel magic or have a survivor bring reinforcements. Why modify when it's so easily overcome?

Personally I like to reward and encourage creativity (like using tiny hut as an ambush tactic) because it makes the game interesting, fun, memorable, and rewarding. I try to prevent boring overuse of the same tactic. Recurring enemies or survivors that flee are valuable here, as they can learn strategies to overcome known tactics.

The enemies can essentially employ siege tactics on a minor scale. Imagine using this in a dungeon, only to wake up surrounded by dozens and dozens of goblins. Sure, they might not be able to get in or get rid of it, but after eight hours it's going to be a pretty big fight. 

You say this is stupid powerful but there’s plenty of rest abilities spells that come online at 6, and for a 3rd level spell I’d say this is easily on par. Counter Spell and Dispell magic are both 3rd level spells as well. 

it is a kind of cheezy spell. in the least it should be breakable. i know it's all situational but this spell is meant to be a tiny free shelter, but i think it's kind of cheezy at 6th level. I'd make it a 4th level spell as is. At level 8 for players you're essentially a super hero in a lot of regards so maybe your players would want to skirt by the survival aspect of adventuring. but level 6 players are still kind of vulnerable. idk i waver back and forth on this one.

Quote from jon_wolf >>

it is a kind of cheezy spell. in the least it should be breakable. i know it's all situational but this spell is meant to be a tiny free shelter, but i think it's kind of cheezy at 6th level. I'd make it a 4th level spell as is. At level 8 for players you're essentially a super hero in a lot of regards so maybe your players would want to skirt by the survival aspect of adventuring. but level 6 players are still kind of vulnerable. idk i waver back and forth on this one.

 As many others have pointed out, it's very easy for a DM to "deal" with this if the DM actually feels like it's their job to punish players for using it. Most would say that it's not the DM's job to do that.

You must be a fun dm to play for

Right?  Its a great spell that breeds creativity. I love tool spells like this.

Also remember that any party member that is outside of it when its cast is also barred from entering, and any enemy that was inside can move freely. Same goes with objects.

Here are a few interesting ways to counter this spell if characters insist on abusing it:

1. Have some large monster come along and take a nap on top of it. Many creatures (like lions in real life) might like high clear vantage points. You could even argue that it might be warmed from inside. As the dome ends it falls into the midst of the group.
2. Have Kobolds or other mischievous critters spread something unpleasant on the dome - Green Slime, Jellies, Acid. The spell ends in a most unpleasant shower.
3. Your enemies could build a huge fire over the dome. Depending on your ruling as a DM the smoke and heat might get them, but even if it doesn't its going to get very warm very fast when the spell ends. Combine this with a surrounding ambush that prevents escape from the fire.
4. In enclosed spaces, like dungeons, denizens could redirect an underground water course to flood the area. DM ruling on whether "comfortable and dry" means it has its own air supply.
5.  In your world if you decide the dome has a floor (seems to be the SA ruling), you could have creatures dig out the space beneath the dome and fill it with something - Spikes, bear traps, or angry nibblers of some kind. Or maybe just have enemy sappers collapse the floor to a lower level of you dungeon.
6. Overnight have some horrible spore-bearing fungus grow over part of the dome.
7. Large monsters, like giants or ogres, could pile massive rocks on top of the dome. The characters will spend their last 8 hours knowing that a crushing death awaits them.

If you're thinking "my characters won't sit there and let any of this happen", that's exactly the point. The idea is to force them out of their indestructible fortress and do something about their imminent demise.If they are the kind that use the dome as cover to poke out try a held action-grapple combo to pull them out or just have some monsters cover the dome with missile weapons while the others work.

To speed up the process just give your enemies access to dispel magic and nullify the dome as soon as the nasty trap of choice is set up.

Jeremy Crawford on Twitter, replied to himself  and corrected a previous error. Leomund's tiny hut does have a floor, Mr. Crawford (read your own book). The spell's range entry says the effect is hemispherical.

P.s. As far as I know, in all previous editions over the past 20 years Leomund's tiny hut has always protected the caster from attacks from below.

In one edition it was a sphere. In a different edition it was a sphere with a floor bisecting it.

delete this, found my answer.