In a couple of story missions, The Last Array and The Siege of the Warmind, you activate a computer terminal and pictures of the Moon, Mars, and Venus come up on the three screens. We are helping upload Rasputin's AI to take control of the "dead" Warmind's defense systems on those planets as well as the one he originally controlled on Earth. Why there aren't Warsat crashes on Venus as public events is unknown, but just because there aren't Warsat crashes on Venus doesn't mean there aren't Warsats orbiting Venus- perhaps they just don't crash. Interestingly enough, the researchers at Ishtar Collective (seen in Ghost Fragments Vex-Vex 5) used an unnamed Warmind to help them explore Vex networks- they used simulated instances of themselves with the Warmind as a "proxy server" of sorts as a firewall between themselves and the Vex single consciousness.

The underground lab you go to for one of the Venus story missions used a warmind to try to out think a vex computer

From what I know from missions and strikes every planet had a AI warmind, also refered to as a ballet fan. In the beginning of the saber strike, ghost says there are few left, one being rasputin. In a mission on mars, your ghost also says the cabal were trying to hack something belonging to the warmind of of mars. Hes apperently been inactive, basically dead, but rasputin has taken over. Venus probably had one based of this. It may be one of the active ones, but judging from how the vex invade everything technilogically, its probably dead as well. Rasputin may have some sense of control over whats left, but I highly doubt it. (Edit)- the only named warmind is rasputin, the others are refered to as the warmind of tere asigned planets.