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

Russian intelligence-linked hackers are targeting users of popular messaging apps like Signal, gaining access to private messages and impersonating victims in a sweeping global campaign, according to a joint warning from the FBI and U.S. cybersecurity officials.

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.

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

Officials said the activity is linked to actors associated with Russian intelligence services.

"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. Instead, it 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.

Patel cautioned that the scheme allows 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," Patel said. 

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 FBI did not provide further comment to Fox News Digital.