Security Experts:

Keyboard Bug Puts Millions of Samsung Galaxy Phones at Risk

More than 600 million Samsung smartphones could be exposed to hacker attacks because the SwiftKey (Samsung IME) keyboard installed on them by default fails to properly validate language pack updates, according to mobile security firm NowSecure.

Researchers say the vulnerability (CVE-2015-2865) is related to the mechanism used for adding new languages and upgrading existing ones. Because the update file is transmitted to the device via HTTP and the authenticity of the data is not properly verified, a man-in-the-middle (MitM) attacker can replace the legitimate update with a malicious payload. This results in the execution of arbitrary code without user interaction.

Since the downloaded file is handled with system privileges, an attacker can exploit the vulnerability to execute code as a privileged user. An attacker can install malicious apps without the user’s knowledge, tamper with how apps and the phone work, eavesdrop on communications, steal sensitive information, and access sensors, GPS, camera, and microphone.

Experts say the vulnerability affects Samsung Galaxy S4 Mini, S4, S5, and S6. Samsung learned of the security bug in December 2014 and started providing a patch to mobile carriers in early 2015. It’s unclear how many of them have delivered the update to their customers, but NowSecure says Verizon and Sprint still haven’t pushed out the patch to Samsung Galaxy S6 phones, T-Mobile hasn’t patched Galaxy S5 phones, and AT&T hasn’t patched Galaxy S4 Mini.

Researchers have pointed out that an attacker has several options for intercepting the targeted user’s communications and modifying upstream traffic. They can use rogue Wi-Fi access points or gain access to the victim’s local network to launch the attack. Remote attacks that involve DNS hijacking, packet injection, rogue routers, or rogue ISPs are also possible, NowSecure said.

Once the attacker has an MitM position, they can inject their malicious payload whenever SwiftKey checks for a language pack update -- on device reboot, or periodically every few hours.

Experts noted that since it comes pre-installed on Samsung devices, the Swift keyboard cannot be disabled or uninstalled. Furthermore, the vulnerability can be exploited even if SwiftKey is not used as the default input method because the software continues to check for updates.

NowSecure says users should contact their carriers to see if a patch is available for this vulnerability. Until the fix is available, users are advised to avoid using untrusted Wi-Fi networks to reduce the risk.

SwiftKey has pointed out that its consumer apps hosted on Google Play and the Apple App Store are not impacted by the vulnerability.

“We supply Samsung with the core technology that powers the word predictions in their keyboard. It appears that the way this technology was integrated on Samsung devices introduced the security vulnerability,” SwiftKey said in a blog post.

Samsung says users can mitigate the vulnerability by using Samsung KNOX, the company's suite of mobile enterprise security solutions.

"Samsung takes emerging security threats very seriously. We are aware of the recent issue reported by several media outlets and are committed to providing the latest in mobile security," Samsung said in a statement.

"Samsung KNOX has the capability to update the security policy of the phones, over-the-air, to invalidate any potential vulnerabilities caused by this issue. The security policy updates will begin rolling out in a few days," the company added. "In addition to the security policy update, we are also working with SwiftKey to address potential risks going forward."

NowSecure has published a video and proof-of-concept (PoC) code to demonstrate the seriousness of the vulnerability.

*Updated with information from SwiftKey and statement from Samsung

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.