Trojan horse
noun
: someone or something that is used to hide what is true or real in order to trick or harm an enemy
computers : a seemingly useful computer program that is actually designed to harm your computer (such as by destroying data files) if you use it
Full Definition
1 : someone or something intended to defeat or subvert from within usually by deceptive means
2 : a seemingly useful computer program that contains concealed instructions which when activated perform an illicit or malicious action (as destroying data files); also : the concealed instructions of such a program — compare virus
Examples
They may be using the other corporation as a Trojan horse.
Origin: from the large hollow wooden horse filled with Greek soldiers and introduced within the walls of Troy by a stratagem.