CWE-345: Insufficient Verification of Data Authenticity - CVE-2015-4640

Samsung Galaxy S phones, including the S4 Mini, S4, S5, and S6, are pre-installed with a version of SwiftKey keyboard that is signed by Samsung to operate with system privileges. By design, SwiftKey periodically checks for language pack updates over HTTP (CVE-2015-4640). By intercepting such requests and modifying the necessary fields, an attacker can write arbitrary data to vulnerable devices.

SwiftKeyhas stated that the "vulnerability is unrelated to and does not affect our SwiftKey consumer apps on Google Play and the Apple App Store."

A remote, unauthenticated attacker conducting a man-in-the-middle attack may be able to write arbitrary data to vulnerable devices checking for updates. Based on the frequency of SwiftKey update checks, which "appears to be every 8 hours" according to NowSecure researchers, such an attack may have a low likelihood of occurring.

Apply an update

Samsung has provided a firmware update to cell phone carriers for distribution to affected users. If your cell phone carrier has not provided the over-the-air update, consider the following workaround:

Avoid untrusted networks

Avoid using untrusted networks, including public WiFi. Using your device on an untrusted network increases the chance of falling victim to a MITM attack.