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LG Patches Serious Vulnerabilities in Smartphone Keyboard

Updates released this week by LG for its Android smartphones patch two high severity keyboard vulnerabilities that can be exploited for remote code execution.

The vulnerabilities were reported to LG late last year by Slava Makkaveev of Check Point Research. The electronics giant patched them with its May 2018 updates, which also include the latest security fixes released by Google for the Android operating system (security patch level 2018-05-01).

According to Check Point, the flaws affect the default keyboard (LG IME) shipped with all mainstream LG smartphones. Researchers successfully reproduced and exploited the security holes on LG G4, G5 and G6 devices.

An attacker could exploit the flaws to remotely execute arbitrary code with elevated privileges by manipulating the keyboard update process, specifically for the MyScript handwriting feature. Hackers can leverage the weaknesses to log keystrokes and capture credentials and other potentially sensitive data.

The first vulnerability is related to installing new languages or updating existing ones. The device obtains the necessary files from a hardcoded server over an HTTP connection, which allows a man-in-the-middle (MitM) attacker to deliver a malicious file instead of the legitimate update.

The second flaw can be exploited by an MitM attacker to control the location where a file is downloaded. A path traversal issue allows hackers to place a malicious file in the LG keyboard package sandbox by including the targeted location in the name of the file.

If the file is assigned a .so extension, it will be granted executable permissions. In order to get the keyboard app to load the malicious file, the attacker can appoint it as an “input method extension library” in the keyboard configuration file. The malware will be loaded as soon as the keyboard application is restarted.

LG noted in its advisory that the vulnerabilities only impact the MyScript handwriting feature.

Reports published last year showed that LG had a 20 percent market share in the U.S. and 4 percent globally. This means there are plenty of devices that hackers could target using the vulnerabilities discovered by Check Point. On the other hand, there are also many critical and high severity flaws in Android itself that hackers could try to exploit and those can pose a bigger risk considering that they could be weaponized against multiple Android smartphone brands.

Related: Unpatched Flaw Exposes LG NAS Devices to Remote Attacks

Related: Flaw Allows Hackers to Modify Texts on LG Smartphones

Related: LG Patches Severe Smartphone Hijack Vulnerability

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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.