The FBI was able to forensically extract copies of incoming Signal messages from a defendant’s iPhone, even after the app was deleted, because copies of the content were saved in the device’s push notification database, multiple people present for FBI testimony in a recent trial told 404 Media. The case involved a group of people setting off fireworks and vandalizing property at the ICE Prairieland Detention Facility in Alvarado, Texas in July, and one shooting a police officer in the neck.
The news shows how forensic extraction—when someone has physical access to a device and is able to run specialized software on it—can yield sensitive data derived from secure messaging apps in unexpected places. Signal already has a setting that blocks message content from displaying in push notifications; the case highlights why such a feature might be important for some users to turn on.