Between 2013 and 2016, the group allegedly hacked computers, smartphones, and tablets belonging to Russian citizens with the sole purpose of stealing their information; and in some cases, this data was then offered for sale on the Dark Web.
The accounts of high ranking Russian officials were also targeted, including the compromise of the Twitter account belonging to Prime Minister Dmitry Medvedev.
In 2014, the account was broken into to post a message claiming that Medvedev was quitting the government to become a freelance photographer, as well as to criticise President Vladimir Putin.
The emails of Russian officials were also offered for sale.
TASS reports that the group's victims also included Medvedev's press secretary Natalia Timakova, Kremlin official Timur Prokopenko, media mogul Aram Gabrelyanov and presidential aide Andrei Belousov.
Members of the group, Alexander Filinov and Konstantin Teplyakov, were found guilty of gaining illegal access to computer information in collusion or within an organized group. While Teplyakov pleaded guilty, Filinov denied the charges.
The Moscow City Court sentenced both to three years in a penal colony each, which are kept away from the general population and usually involve forced labor.
Filinov's legal team is considering an appeal, as they believe a penal colony is a "disproportionate punishment."
Another member of the Humpty Dumpty group, Vladimir Anikeyev, was sentenced earlier this year. Anikeyev is believed to be the leader of the hackers, and after pleading guilty to the same charges was sentenced to two years in prison.
A fourth alleged member of the group is at large abroad, and another alleged member, journalist Andrei Nekrasov, has been granted political asylum in Lithuania.