Officers at Lockerbie say ‘catastrophic consequences’ were luckily avoided, but an Audi A6 had windscreen damage estimated at about £350.
Police Scotland explained the act of reckless conduct happened at an overbridge between junctions 17 and 18 at about 2.30 pm.
No one was injured but the vehicles was extensively damaged.
Constable Jordan Kerr of Police Scotland at Lockerbie said: “This was and act of utter recklessness and the consequences could have been catastrophic.
“We are very lucky that we are not dealing with serious injury here and I would urge anyone who may have any information which may help us catch those responsible to call me at Lockerbie on 101.”