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Samsung Galaxy S phones fail to properly validate SwiftKey language pack updates

Vulnerability Note VU#155412

Original Release Date: 2015-06-16 | Last Revised: 2015-06-25


Samsung Galaxy S phones, including the S4 Mini, S4, S5, and S6, fail to properly validate Swiftkey language pack updates.


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.

SwiftKey has 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.

Vendor Information


Samsung Affected

Notified:  March 02, 2015 Updated: June 16, 2015

Statement Date:   March 07, 2015



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.


Samsung Galaxy S phones, including the S4 Mini, S4, S5, and S6, are affected by this vulnerability.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group Score Vector
Base 5.7 AV:A/AC:M/Au:N/C:N/I:C/A:N
Temporal 4.5 E:POC/RL:OF/RC:C
Environmental 4.5 CDP:N/TD:H/CR:ND/IR:ND/AR:ND



Thanks to Ryan Welton and Ted Eull of NowSecure for reporting this vulnerability.

This document was written by Joel Land.

Other Information

CVE IDs: CVE-2015-4640, CVE-2015-4641
Date Public: 2015-06-16
Date First Published: 2015-06-16
Date Last Updated: 2015-06-25 21:25 UTC
Document Revision: 33

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