The public prosecutor’s office in Karlsruhe has opened an investigation into an ongoing phishing campaign targeting users of the messaging app Signal. According to a spokesperson, the investigation focuses on suspicions of intelligence agency activity and potential espionage.
The seriousness of the incident was underscored when it was reported that the Signal account belonging to Julia Klöckner, the President of the Bundestag and a CDU member, was successfully compromised by attackers. This breach is considered highly significant because Klöckner is also a CDU party committee member, and key members of the party leadership, including party conference sources and Chancellor Friedrich Merz, also use Signal for internal communication.
The investigations in Karlsruhe have been running since mid-February. At that time, both the Federal Office for the Protection of the Constitution (BfV) and the Federal Office for Information Security (BSI) publicly issued warnings about the active phishing campaign. In a recent urgent advisory, the BfV noted that it was already aware of “numerous high-profile cases” and anticipates a much larger number of affected individuals that have yet to be reported.
The targets of the campaign are not limited to politicians; information sourced from “Der Spiegel” indicates that high-ranking business leaders, prominent journalists, and personnel within NATO forces have also been affected. Historically, Signal accounts belonging to NATO members-though reportedly not involving German Bundeswehr personnel-were noted to have been briefly taken over by attackers on private phones.
The security risk has been highlighted repeatedly. The Military Counterintelligence Service (MAD), responsible for espionage countermeasures within the Bundeswehr, issued an urgent public warning about the attackers’ schemes on January 6. Meanwhile, Dutch intelligence services had previously blamed Russian state actors for the current wave of attacks during March. While the Bundestag’s key figures remain targets, the Signal account of Chancellor Friedrich Merz was reported to show no specific irregularities when contacted personally by BfV employees.
