CVE-2019-9939 in SHAREit
Summary
by MITRE
The SHAREit application before 4.0.36 for Android allows a remote attacker (on the same network or joining public "open" Wi-Fi hotspots created by the application when file transfer is initiated) to bypass authentication by trying to fetch a non-existing page. When the non-existing page is requested, the application responds with a 200 status code and empty page, and adds the requesting client device into the list of recognized devices.
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Analysis
by VulDB Data Team • 08/04/2023
The vulnerability identified as CVE-2019-9939 represents a critical authentication bypass flaw in the SHAREit application version 4.0.35 and earlier for Android platforms. This security weakness stems from the application's improper handling of network requests during the file transfer initiation process, creating an exploitable condition that allows remote attackers to gain unauthorized access to the device's file sharing capabilities. The vulnerability specifically affects devices that create public Wi-Fi hotspots through the SHAREit application, making it particularly dangerous in network environments where multiple users may connect to the same wireless network.
The technical implementation of this flaw involves the application's response handling mechanism when processing HTTP requests from connected devices. When an attacker sends a request to a non-existent page within the application's web server, the system incorrectly responds with a 200 status code indicating success, along with an empty page content. This malformed response triggers the application's device recognition logic, which automatically adds the requesting client device to the list of authorized devices without proper authentication verification. The vulnerability essentially allows attackers to spoof legitimate device recognition through crafted HTTP requests, effectively bypassing the application's intended access control mechanisms. This behavior aligns with CWE-287, which addresses improper authentication issues in software systems.
The operational impact of this vulnerability extends beyond simple unauthorized device recognition, as it provides attackers with persistent access to the file sharing functionality of the compromised device. Once added to the recognized devices list, attackers can potentially initiate file transfers, access shared content, and maintain ongoing access to the device's resources without requiring legitimate credentials or user interaction. The vulnerability is particularly concerning in public Wi-Fi environments where attackers can easily join networks created by SHAREit applications and exploit this weakness to gain unauthorized access. The attack vector requires minimal technical expertise, as it only requires sending specific HTTP requests to the device's web interface, making it accessible to attackers with basic networking knowledge and aligning with ATT&CK technique T1071.004 for application layer protocol: web protocols.
Mitigation strategies for this vulnerability should focus on implementing proper authentication mechanisms and input validation within the application's network handling components. The recommended approach involves updating the SHAREit application to version 4.0.36 or later, which addresses the flawed device recognition logic by properly validating all incoming requests and ensuring that only legitimate authentication attempts result in device recognition. Network administrators should also implement additional security measures such as monitoring for unusual HTTP request patterns and configuring network access controls to limit unauthorized device connections. The vulnerability demonstrates the importance of proper error handling in web applications and highlights the need for robust authentication protocols even in peer-to-peer file sharing contexts, as specified in security best practices for mobile application development and network security standards.