Mittwald, a web host based in Espelkamp, reports on the breach and its investigation on its status page and FAQ page. On 12 November, the German technology outlet heise online reported that the company was still in crisis mode a week after the first attack.

What the MCP server exposed

Mittwald said the MCP server was an interface that let customers connect mStudio, the company’s management environment, to AI assistants. On 4 November, the company discovered through its own analysis that someone had gained unauthorised access to the server on 27 October. The attacker read access tokens belonging to users of the interface.

A token gave access to mStudio with the user’s permissions and to the projects the user could access. Mittwald is checking each of these projects individually and temporarily suspending any in which it finds traces of the attacker. As a precaution, it has disabled a small share of projects. No passwords were taken, and the tokens have been revoked, the company said. Mittwald explained that it noticed the breach only a week later because the attacker made the preparations look like ordinary user activity.

Mittwald is notifying those affected individually by email. It advises customers who used the MCP server to change their mStudio password and enable two-factor authentication. They must also check their projects’ API keys, project tokens and SSH keys, remove unfamiliar entries and renew third-party credentials stored in projects. SSH users that the customer did not create are particularly suspicious, the company said. Mittwald considers any use of the server from 27 October onwards potentially compromised.

The MCP server remains offline for now, and Mittwald is offering its CLI tool instead. Based on what the company currently knows, customers who have received no email and have not set up the MCP server need not take action, though Mittwald recommends two-factor authentication.

Second wave of attacks on 12 November

Mittwald reopened mStudio and SSH access on 7 November. The company said the attackers resumed their attacks on the night of 12 November, and Mittwald shut down its customer centre, mStudio and all SSH connections as a precaution. It describes the attackers as professionals who use automated AI systems.

Accounts of the company’s own website conflict. Mittwald’s status page said the attackers exploited a vulnerability and compromised the site, after which the company took it offline. An anonymous tipster told heise that the site had been defaced with the attackers’ content. Mittwald denied this to heise: it had taken the site offline itself as a precaution, and the site was neither hijacked nor defaced.

By the morning of 12 November, the company had detected no access to its internal systems and was continuing to analyse the attack methods. The shutdown does not affect customers’ websites and email, Mittwald said. Customers are complaining about outages in the management interface and SSH, heise reported.

On the afternoon of 12 November, Mittwald expected to reopen the customer centre and mStudio by 11:00 on 13 November at the latest. The SSH block will stay in place until checks and scans are complete, the company said.