A lock assembly includes a lock body and a U-shaped shackle having a curved portion extending between first and second legs receivable in first and second shackle apertures in an upper portion of the lockbox body. The shackle has a guard wall affixed to an interior surface of the curved portion, the guard wall defining an interior arcuate wall surface extending forward and rearward from a central plane bisecting the shackle. The upper portion of the lock body includes first and second protruding projections at least partially surrounding the first and second shackle apertures and defining first and second upwardly diverging interior surfaces laterally aligned with the curved portion of the shackle. The lock body includes a latching mechanism configured to secure the shackle in a plurality of latched positions to adjust a distance between the first and second upwardly diverging interior surfaces and the curved portion of the shackle. When the shackle is secured around a door handle with the shackle secured in a suitable one of the plurality of latched positions, abutment of the interior arcuate wall surface with a neck portion of the door handle impedes forward and rearward rotation of the lock assembly about a horizontal axis extending through the curved portion of the shackle and abutment of the first and second upwardly diverging interior surfaces with a neck portion of the door handle impedes side-to-side twisting rotation of the lock assembly about a vertical axis extending through the curved portion of the shackle.