Foreign state-backed hackers are targeting accounts on WhatsApp and Signal used by government officials, diplomats, military personnel, and other high-value individuals, according to a security alert issued by the Portuguese Security Intelligence Service (SIS).
Portuguese authorities described the activity as part of a global cyber-espionage campaign aimed at gaining access to sensitive communications and extracting privileged information from Portugal and allied countries. The advisory did not identify the origin of the suspected attackers.
The warning follows similar alerts from other European intelligence agencies. Earlier this week, Dutch authorities reported that hackers linked to Russia were conducting a global campaign targeting the messaging accounts of officials, military personnel, and journalists.
Security agencies say the attackers are not exploiting vulnerabilities in the messaging platforms themselves. Both WhatsApp and Signal rely on end-to-end encryption designed to protect the content of messages from interception.
Instead, the campaign focuses on social engineering tactics that trick users into granting access to their accounts. According to the SIS report, attackers use phishing messages, malicious links, fake technical support requests, QR-code lures, and impersonation of trusted contacts.
The agency also warned that AI tools are increasingly being used to make such attacks more convincing. AI can help impersonate support staff, mimic familiar voices or identities, and conduct more realistic conversations through messages, phone calls, or video.
Once attackers gain access to an account, they may be able to read private messages, group chats, and shared files via WhatsApp and Signal. They can also impersonate the compromised user to launch additional phishing attacks targeting the victim’s contacts.
The alert echoes a previous warning issued by the Cybersecurity and Infrastructure Security Agency (CISA), which reported that encrypted messaging apps are increasingly being used as entry points for spyware and phishing campaigns targeting high-value individuals.
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