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LG Fixes Authentication Bypass Vulnerability in On-Screen Phone App

Researchers have uncovered a vulnerability in LG’s On-Screen Phone (OSP) application that can be exploited by an attacker to take complete control of affected smartphones.

LG On-Screen Phone allows users to control their smartphones from a PC. The connection between the mobile device and the computer can be done via a USB cable, Wi-Fi or Bluetooth. For the connection to be authenticated, a dialog box displayed on the phone asks the user for confirmation.

The problem, according to researchers at Hungary-based Search-Lab, is that this authentication mechanism can be bypassed.

Normally, the connection is closed if it’s not confirmed by the user. However, an attacker can use a modified client to connect to the smartphone and perform various actions (e.g. submit files, carry out touchscreen actions) directly, without the confirmation window being displayed.

“A malicious attacker is able to bypass the authentication phase of the network communication,

and thus establish a connection to the On Screen Phone application without the owner’s knowledge or consent,” researchers explained in a post on Full Disclosure. “Once connected, the attacker could have full control over the phone – even without physical access to it. The attacker needs only access to the same local network as the phone is connected to, for example via Wi-Fi.”

The authentication bypass vulnerability (CVE-2014-8757) affects OSP version 4.3.009 and prior.

Researchers have pointed out that the application is preinstalled on some LG smartphones. This makes the devices vulnerable by default because the the app starts automatically on boot and it cannot be disabled.

The security hole was reported to LG in September 2014. The company addressed the issue with the release of OSP 4.3.010, which can be downloaded from the LG Update Center. For some phone models, the new version will be made available as a maintenance release, Search-Lab said in its advisory.

The researchers have published a proof-of-concept (PoC) video to demonstrate their findings.

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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.