In early 2020, the Iran-backed Shia rebels of Iran released photos of former Yemen Air Force air-to-air missiles that had been converted, with Iranian assistance, to operate as SAMs (Surface To Air Missiles.) The rebels say they have been using these Russian missiles as SAMs since 2017 and in 2018 they claimed to have used it to shoot down a Saudi F-15S fighter-bomber. That F-15S did not crash but did report it was fired on by some kind of SAM. More recently the rebels claimed to have downed a Saudi Tornado jet fighter the same way. But the Tornado went down because the two-man crew had problems with their oxygen supply plus a fire in the cockpit. The pilots ejected and were later picked up by a Saudi helicopter. Yet the rebels probably really had adapted the Russian missiles for ground use.
The Yemeni Air Force had plenty of Russian R-73 heat-seeking air-to-air missiles and the larger R-77 radar-guided air-to-air missiles. These were captured by the Shia rebels when they overran most of northern Yemen in 2014 and many Yemeni military units sided with the rebels. Converting these two missiles is not difficult but does require engineers and skilled technicians to do it. For example in 1999 the Serbian Air Force did it and used their Russian air-to-air missiles regularly as SAMs. For decades Iran has been adapting American and Russian weapons for new uses and they are apparently behind the conversion of Yemeni Russian heat-seeking and radar-guided air-to-air missiles as SAMs. Adapting the smaller, and shorter ranged heat-seeking air-to-air missiles is pretty straightforward. You have to build a ground launcher, which you can mount in the back of a pickup truck. Then you have to build (or take from an aircraft) the simple electronics used by the pilot to arm (activate the infrared seeker) and fire the missile. The radar-guided R-77 is more complex because it requires a separate radar, which is normally carried in the nose of the aircraft, to track the target and communicate with the R-77 after launch to get the missile close enough to the target so the heat-seeking guidance also found in the R-77 can take over. Russia also sells a shorter range R-77 that just uses the heat-seeker. In other words, the mods are not high-tech but they are techy. Such modifications are nothing new.
In the 1960s the U.S. Army developed a system where vehicles equipped with a Sidewinder heat-seeking air-to-air missile were used as a SAM. This system was called Chaparral and served the U.S. Army from the late 1960s to the late 1990s.
The latest U.S. radar-guided missile, AMRAAM, has its own radar for making its final approach to its target. That led Norway to create its NASAMS anti-aircraft system using AMRAAM as a SAM. This proved very effective and popular. NASAMS has been seen deployed around Washington DC since 2002, as a defense against any terrorist aircraft attempting to attack. Other early users of NASAMS were Spain and Kuwait.
A box launcher is used by NASAMS. The ground-launched AMRAAM can hit targets as high as 4,200 meters (13,000 feet). NASAMS was developed so that it could easily work with different search radars. The AMRAAM SAM costs more (about $600,000 each) compared to the air-to-air version (about $380,000), but is basically the same missile. The four meter (twelve foot) long AMRAAM has a 22.7 kg (fifty pound) warhead, and can take down just about anything that flies, including wide-body commercial transports.