The next to last major movement of Mussorgsky's "Pictures at an
Exhibition" is a musical depiction of Victor Hartmann's painting
derived from a Russian legend. On what does the hut in the legend
stand?

The hut stands on fowl's legs (or hen's legs, or chicken legs).

"Baba-Yaga is the witch of death from Russian mythology. In the story,
she lives in 'The Hut on Fowl's Legs'. Hartman painted a design for a
clock based on the hut. This is another quite dark movement in the
music."

BBC: 'Pictures at an Exhibition' by Modest Mussorgsky
http://www.bbc.co.uk/dna/h2g2/alabaster/A536410

"The Hut On Fowl's Legs (Baba-Yaga)
Hartmann's design was for an ornate clock inspired by the ancient
folktale of the Baba Yaga, the witch who lives in a house on chicken
legs.

Mussorgsky's music depicts the witch flying through the air in her
mortar in which she grinds human bones. She flies into a forest, her
hut following her on the ground. The music is subdued and menacing.
Then all of a sudden she re-appears, hurtling through the sky,
straight into the final piece of music."

Good Music Guide: Modest Mussorgsky - Pictures at an Exhibition
http://www.good-music-guide.com/reviews/057_mussorgsky_pictures.htm

Google search strategy:

Google Web Search: "pictures at an exhibition" + "hut" + "legs"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22pictures+at+an+exhibition%22+hut+legs

I hope this helps! Please request clarification if anything is unclear
or incomplete.

Best regards,
pinkfreud

Excellent!