Consider a program to accept and tabulate votes in an election. who might want to attack the program? what types of harm might they want to cause? what kinds of vulnerabilities might they exploit to cause harm?

Who might want to attack the program to accept and tabulate votes in an election?

The political opponents.

What types of harm might they want to cause?

A silent interception; an interruption  a modification and a fabrication

What kinds of vulnerabilities might they exploit to cause harm?

The assets vulnerablities.  

Explanation:

Political opponents might want to attack the program to accept and tabulate votes in an election to modify factual results to show them as the winners.

The harm they might want to cause is cheating the elections by copying the program, data files or wiretapping; to get the system lost, or get it unavailable or unusable with the factual data in the large dams and disable the power grids and modify the values accordingly adding the forged results.