Home addresses, cell phone numbers, credit and ID cards, private chats between family members, job applications, party memos and lists of party members were leaked; some of the documents are over a year old. Nearly all politicians from major parties have had their personal information stolen and leaked, with the exception of the far-right AfD.
The German Federal Office For Information Security (BSI) has said it is investigating and emphasised that there is no evidence that government systems have been hacked, only individuals.
He said it made flawless sense that none of the targets in this hacking campaign was from Germany's far right, and that it appeared aimed at "undermining the German political process and essentially stoking fires of the mob".
Preliminary review of the documents discovered no sensitive information.
German politicians and prominent newsmakers have fallen victim of what appears a brazen hack attack on their private data.
The German government warned that some of the leaked documents could have been doctored, and said it's still verifying all the leaked data.
As Twitter's European headquarters are located in Dublin, the leak falls under the remit of the Irish data protection authority, national broadcaster RTE reports. The country's internal computer networks have not been breached, according to Bild.
The Twitter account @-0rbit published the links on a daily basis in the style of an advent calendar, with each entry representing a "door", behind which was a link to new information.
She said: "We are calling upon citizens that the data that has been published should be viewed with caution and to not take everything par for par".
It described its activities as "security researching", "artist" and "satire and irony" and said it was based in Hamburg. The first post published on December 1 and the hacker was posting daily updates until Friday, when Twitter suspended the account.
In 2015, members of the Bundestag were targeted by the Russian threat group known as APT 28 (also known as Fancy Bear-the GRU intelligence operation identified and indicted by the US Justice Department). News agency dpa reported that the information included a fax number and email address belonging to Merkel and several letters to and from the chancellor.
The security source told Bild that the government's networks were not fending off any sustained attack.
Though the Twitter account was suspended, the hacker provided multiple back-up links for people to download the breached files.
Tom Kellermann, the chief cybersecurity officer of Carbon Black, said the latest hack had all the hallmarks of Russian state-backed hackers.