FBI warns Russian hackers targeting Americans on Signal, thousands of accounts compromised

The FBI and the Cybersecurity and Infrastructure Security Agency said the operation has already compromised "thousands of individual" commercial messaging app (CMA) accounts, allowing attackers to read messages, access contact lists and send messages posing as the victim.

FBI Director Kash Patel warned the campaign is targeting individuals of "high intelligence value," including U.S. officials, military personnel and journalists, and has already resulted in widespread account compromises.

Patel warned the attackers can exploit compromised accounts to impersonate victims and target others using a trusted identity.

"After compromising an account, malicious actors can view the victims' messages and contact lists, send messages, and conduct additional phishing against other CMA accounts."

Officials said the activity is linked to actors associated with Russian intelligence services and targets individuals considered to be of "high intelligence value," including current and former U.S. government officials, military personnel, political figures and journalists.

"RIS actors have compromised individual CMA accounts, but not CMAs' encryption or the applications themselves," the FBI and CISA said.

The agencies emphasized the activity does not involve breaking Signal's encryption, but instead relies on tricking users through phishing schemes.

"Phishing remains one of the most unsophisticated, yet effective means of cyber compromise, often rendering other protections irrelevant including end-to-end encryption," the agencies said.

If a user complies, attackers can link their own device to the account or take it over entirely, allowing them to monitor private conversations and impersonate the victim.

FBI Director Kash Patel cautioned that the scheme allows for cybercriminals to "conduct additional phishing."

"After gaining access, the actors can view messages and contact lists, send messages as the victim, and conduct additional phishing from a trusted identity."

The PSA said users who believe they may have been targeted should report incidents to the FBI's Internet Crime Complaint Center.

The link to "cyber actors" associated with Russian Intelligence was not made more specific in the agencies' joint PSA.

Signal did not immediately respond to Fox News Digital's request for comment. The Federal Bureau of Investigation did not provide further comment to Fox News Digital.