Add custom field for all records with a logged value

In my log file there is a line with "hash: "
I need to parse this value and set to all records in this file (at least for all those which go right after this record).

01/03/2016: log init
01/03/2016: hash = 452345
01/03/2016: hello
01/03/2016: from
01/03/2016: logs

and this should be parsed to the:

{
"title": log init",
"hash": "452345"
}
{
"title": hash = 452345",
"hash": "452345"
}
{
"title": hello",
"hash": "452345"
}
{
"title": "from",
"hash": "452345"
}
{
"title": "logs",
"hash": "452345"
}

at least that would be great to add this hash to all records after "hash = ..."