Even Mad-Eye Moody's famed paranoia has limits - apparently rodent proofing his house exceeded them.
From an entirely unrelated series:
“You want to send in harnessed ferrets through a laundry vent?” Augustine clearly had difficulty coming to terms with that idea.
“Yes,” Cornelius said.
I blinked. “Wouldn’t the vent be secured by an alarm?”
The three of them looked at me as if I’d suddenly sprouted a second head.
“It doesn’t make sense to secure a laundry vent,” Rogan explained. “It’s too small and it opens into a dryer.”
“I’m more paranoid than Baranovsky,” Rogan said. “My laundry vents aren’t secured. But I’d imagine there is a metal grate over them.”
“Does anybody else find this whole idea of a ferret heist mildly absurd?” Augustine looked around the room.
“Grates are not an issue,” Cornelius said.
“Can your animals handle screws?” Augustine asked.
Cornelius met his gaze. “Let’s assume that I spend as much time training my animals and honing my magic as you do practicing your illusions.”
“How confident are you that this will work?” I asked Cornelius.
He smiled at me.
“Let’s do it,” Rogan said.
- White Hot, by Ilona Andrews
As an intelligent rodent, Wormtail possess unparalleled advantages when it comes to breaking and entering. Once he was inside, he could disable the alarms and let Crouch in. He probably wouldn't be able to turn off everything, but all he needs to do is get Crouch in fast enough to get the jump on Moody before he's fully awake. Two fully prepared wizards against one half-asleep one is no contest, even if the half-asleep wizard is Alastor Moody. Even so, he put up enough of a fight to be noticed by the neighbors, which is pretty impressive.