Signal accounts hijacked via social engineering

French CERT-FR warns of targeted campaigns hijacking Signal and WhatsApp accounts through social engineering, affecting government officials, journalists, and critical sectors.

The French national cybersecurity agency CERT-FR has observed a surge in targeted attacks against instant messaging accounts, particularly Signal and WhatsApp. The campaigns primarily target government officials, political figures, civil servants, journalists, and industrial personnel in sensitive roles. Attackers exploit legitimate platform features rather than technical vulnerabilities to gain partial or complete account control.

The attacks follow two main patterns: victims receive messages inviting them to join group chats by scanning QR codes, which actually link their accounts to attacker-controlled devices, or attackers impersonate support staff to trick victims into disclosing security codes or PINs. In observed campaigns, attackers use accounts named "Signal Support" or "Signal Security ChatBot" to appear legitimate. Once successful, attackers can access conversation histories, maintain persistent access even while victims retain their accounts, or completely take over accounts by changing associated phone numbers.

CERT-FR emphasizes that the attacks target the messaging applications themselves rather than compromising the underlying mobile devices. The agency has issued detailed mitigation guidance including enabling PIN protection, never responding to unsolicited messages claiming to be from support, never scanning received QR codes, and regularly auditing linked devices. This alert was issued jointly by France's Cyber Crisis Coordination Centre (C4) members.

Source reporting: https://www.cert.ssi.gouv.fr/alerte/CERTFR-2026-ALE-003