CVE-2017-17551 in Dolphin Browser
Summary
by MITRE
The Backup and Restore feature in Mobotap Dolphin Browser for Android 12.0.2 suffers from an arbitrary file write vulnerability when attempting to restore browser settings from a malicious Dolphin Browser backup file. This arbitrary file write vulnerability allows an attacker to overwrite a specific executable in the Dolphin Browser's data directory with a crafted malicious executable. Every time the Dolphin Browser is launched, it will attempt to run the malicious executable from disk, thus executing the attacker's code.
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Analysis
by VulDB Data Team • 12/13/2019
The vulnerability identified as CVE-2017-17551 represents a critical arbitrary file write flaw within the Backup and Restore functionality of Mobotap Dolphin Browser version 12.0.2 for Android platforms. This security weakness stems from inadequate input validation and insufficient file system access controls during the restoration process, creating an exploitable condition that can be leveraged by malicious actors to execute unauthorized code within the context of the affected application. The vulnerability specifically manifests when the browser attempts to restore settings from a maliciously crafted backup file, allowing attackers to manipulate the file system in ways that were not intended by the application's developers.
The technical exploitation of this vulnerability occurs through a carefully constructed malicious backup file that, when processed by the browser's restore mechanism, triggers an arbitrary file write operation. The flaw enables an attacker to overwrite executable files within the Dolphin Browser's designated data directory with malicious payloads. This particular attack vector operates under the principle of privilege escalation through application-level file system manipulation, where the browser's normal execution context becomes compromised when it attempts to restore user data. The malicious executable, once written to the designated location, becomes persistent within the application's operational lifecycle, as the browser automatically attempts to execute this file every time it is launched.
The operational impact of this vulnerability extends beyond simple code execution, as it creates a persistent backdoor within the user's device that can be leveraged for various malicious activities. When the Dolphin Browser launches, it automatically executes the malicious payload, potentially enabling attackers to gain unauthorized access to user data, monitor browsing activities, or establish further footholds within the device. This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and represents a classic example of how backup and restore features can introduce security risks when not properly validated. The attack scenario follows patterns consistent with the ATT&CK framework's persistence techniques, specifically targeting application execution hooks to maintain long-term access.
Mitigation strategies for CVE-2017-17551 require immediate attention from users and system administrators, with the most effective approach being the immediate uninstallation of the vulnerable browser version until a patched release is available. Users should avoid downloading backup files from untrusted sources and should verify the integrity of any backup files before attempting restoration operations. Application developers should implement strict input validation for backup files, employ proper file system access controls, and consider implementing sandboxing mechanisms to limit the impact of potential file system manipulations. Additionally, the vulnerability highlights the importance of secure coding practices in mobile applications, particularly regarding the handling of user-provided data in sensitive contexts such as backup restoration processes. Organizations should monitor for similar vulnerabilities in other browser applications and implement network-level controls to detect and prevent malicious backup file transfers. The security community should also consider this vulnerability as a case study in how seemingly benign application features can become attack vectors when proper security controls are not implemented.