Understairs Bug - Iberian Offensive

Found this interesting bug on Iberian Offensive. There is a spot on the map with a staircase, that goes through a corridor-like place. In the very corner you can see that the stairs is missing a texture, you can jump down in this hole below the stairs if the white spouting on the wall is broken (ie. HE Grenade)

Most of the area you can't shoot through, but there is a specific angle in the corner where you jump down that will let you shoot enemies that pass.