How the Impostation Unfolded
In mid‑June 2025, an impostor reached out to three foreign ministers, a state governor, and a member of Congress while posing as Secretary of State Marco Rubio. The fraudster created a Signal account under the display name “Marco.Rubio@state.gov” and sent both text messages and voice notes.
The messages asked recipients to continue conversations on Signal, promising to share sensitive policy updates. The targets noticed subtle oddities in tone and phrasing and flagged the messages to their security teams. At that point, the plot came to light and triggered a rapid review by the State Department.
Voice Cloning Technique Overview
The campaign relied on modern AI voice cloning tools that analyze speech samples to recreate pitch, tone, and timing. The impostor fed five seconds of publicly available recordings into a model and then refined the output with additional data harvested from speeches. This process delivered a synthetic voice nearly identical to Rubio’s natural speech.
After that, the fraudster scripted text in Rubio’s style by scanning his published statements and matching sentence length. The result tricked several recipients until they noticed minor word choices that did not match Rubio’s usual phrasing.
State Department Response
On July 3, 2025, the State Department issued a cable to all embassies and consulates warning of the impersonation attempt. Senior officials called the tactic “prudent to share” and noted that the breach did not succeed in extracting classified data.
They also confirmed that other State Department staff members became targets by email. The FBI already raised alarm about similar text and voice campaigns earlier in the year after reports of attackers mimicking high‑profile figures.
Signal App Risks
Signal’s encrypted protocol remains strong, but the app’s “linked devices” feature carries risk. Threat actors craft fake QR codes that victims scan, linking their account to attacker devices. Once that link exists, the fraudster can read all messages in real time. Security researchers tie this method to groups like UNC5792 and APT44, which used it on the Ukrainian front. In addition, past flaws such as CVE‑2023‑24068 allowed malicious actors to swap attachments and CVE‑2022‑28345 let them impersonate link targets. These gaps show that even secure apps need constant audits and user caution.
Personal Analysis
This incident marks a turning point in digital trust. It proves that minimal data, like a short audio clip, can grant fraudsters access to high‑level officials. That fact should urge departments to adopt multi‑factor voice authentication and treat AI clones as a core threat. Agencies must train staff to spot odd phrasing and verify identities with secondary channels. In my view, governments and private firms need to invest in rapid audio forensics and real‑time anomaly detection to stop these campaigns at the outset.
Sources: France 24
