Days after the Signal leak, the Pentagon warned the app was the target of hackers
Several days after top national security officials accidentally included a reporter in a Signal chat about bombing Houthi sites in Yemen, a Pentagon-wide advisory warned against using the messaging app, even for unclassified information.
“A vulnerability has been identified in the Signal Messenger Application,” begins the department-wide email, dated March 18 and obtained by NPR.
The memo continues, “Russian professional hacking groups are employing the ‘linked devices’ features to spy on encrypted conversations.” It notes that Google has identified Russian hacking groups that are “targeting Signal Messenger to spy on persons of interest.”
Moreover, a memo in 2023, obtained by NPR, warned of using Signal for any nonpublic official information.
A Signal spokesman said the Pentagon memo is not about the messaging app’s level of security, but rather that users of the service should be aware of what are known as “phishing attacks.” That’s when hackers try to gain access to sensitive information through impersonation or other deceptive tricks.
“Once we learned that Signal users were being targeted and how they were being targeted, we introduced additional safeguards and in-app warnings to help protect people from falling victim to phishing attacks. This work was completed months ago,” said Signal spokesman Jun Harada.
The March 18, 2025, Pentagon memo adds, “Please note: third party messaging apps (e.g. Signal) are permitted by policy for unclassified accountability/recall exercises but are NOT approved to process or store nonpublic unclassified information.”
The encrypted Signal app is what Defense Secretary Pete Hegseth and other leading national security officials within the administration used to discuss bombing Houthi sites this month. The Atlantic‘s editor-in-chief, Jeffrey Goldberg, was inadvertently added to the group and was privy to the highly sensitive discussions.
In the military, sending classified data over insecure channels is called “spillage”; it can be a career ender for a military officer. [Continue reading…]