As per FAS.org Babur-I is said to be a badge-engineered Korshun missile sourced from Ukraine 

Pakistan’s efforts to build a 750 km range ground-launched cruise missile Babur-II have suffered a set-back with the delivery platform crashing to the ground after two minutes or 14 kilometres in flight from the launch point at Sonmiani test range in Baluchistan on March 19.

According to national security planners and Pakistan watchers, this was the second consecutive test failure of the Babur II sub-sonic missile after the previous test failed on April 10, 2018.

The second test launch failed while being witnessed by Lt Gen Sahir Shamshad Mirza, Chief of General Staff, Pakistan General Headquarters, Rawalpindi, and top officials of Army Strategic Forces Command (ASFC) and Strategic Plans Division.

Senior officials told Hindustan Times that Pakistan with the help of China is trying to build missile named after first Mughal Emperor Babur to match the 1,000 kilometre range Nirbhay cruise missile being developed by the DRDO.

Both the missiles are said to have terrain hugging and sea skimming capabilities with nuclear as well as conventional warhead.

The Nirbhay missile has already undergone six test trials with the last one achieving full mission objectives.

It is understood that before testing Babur-II missile, a team of Pakistan missile scientists had visited China. Islamabad has already developed a 700 kilometre range Babur I cruise missile that can be fired both from land as well as sea with terrain contour matching and GPS satellite guidance.

It is also trying to develop air launched cruise missile by the name RAAD.

The Pakistani cruise missiles are derivatives of Chinese C-602 and C-802 missiles with both the countries not members of missile technology control regime.