malevolent activity

This is a compositional prepositional phrase, not a term of art with a specialized or stipulated meaning. It functions as the condition-modifier in a risk statement: it describes the circumstance in which harmful, intentional acts by insiders — fraud, sabotage, unauthorized disclosure — can be carried out by a single individual acting alone, without needing to coordinate with or depend on another person. Separation of duties addresses the potential for abuse of authorized privileges and helps to reduce the risk of malevolent activity without collusion — meaning that when duties are properly divided, no one person retains enough unilateral access or authority to complete a harmful act on their own. The phrase is used across access-control and insider-threat literature as shorthand for the residual single-actor threat that separation of duties is designed to neutralize, and its meaning is entirely derivable from its component words in ordinary English.