Ms Griner, who was arrested in Moscow and given a nine-year prison sentence, was exchanged for Viktor Bout, a Russian arms dealer.
The cyberattack affected the websites of the president, the government, key ministries and the Constitutional Court.
Moscow hastily convened referendums in four Russia-occupied Ukrainian regions to justify a move to incorporate them into the Russian Federation.
The West African country has deepened its Soviet-era ties to Russia as its relationship soured this year with its long-time ally and former colonial ruler, France.
In addition to shipping millions of tonnes of food from Ukraine, the initiative also envisages the export of fertiliser needed by the world’s farmers.
The 161 member states, including Nigeria, voted in favour of the resolution, while eight abstained from voting.
