Zero Day Flaws in Browsers for Android

Monday, August 24, 2015 @ 04:08 PM gHale

Dolphin and Mercury web browser users on Android should think about switching to other applications after a researcher found a series of Zero Days.

Dolphin Browser for Android has between 50 million and 100 million installs, while Mercury Browser for Android has between 500,000 and 1 million installs, according to information from Google Play.

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A mobile security researcher known as “rotlogix” reviewed the browsers.

The Dolphin browser has a vulnerability that can end up exploited by a man-in-the-middle (MitM) attacker for arbitrary file writing and even remote code execution, the researcher said. Dolphin developers are aware of the security hole.

The flaw relates to a feature that allows users to download and apply themes for the web browser. Because the themes end up downloaded over HTTP, an MitM attacker can inject a specially crafted file.

Rotlogix said a malicious actor could create a theme file that can modify an existing Dolphin library loaded at startup ( in order to execute arbitrary code.

“Through the exploitation of this functionality, an attacker can achieve an arbitrary file write, which can then be turned into code execution within the context of the browser on the user’s device,” the researcher explained in a blog post. “The only user interaction this requires is selecting, downloading, and applying a new Dolphin Browser theme.”

Mercury Browser for Android users are exposed to attacks due to a couple of unpatched vulnerabilities that can be combined by a remote attacker to read and write arbitrary files within the application’s data directory.

“The Mercury Browser for Android suffers from an insecure Intent URI scheme implementation and a path traversal vulnerability within a custom web server used to support its WiFi Transfer feature,” the researcher said in a post.

A remote attacker can exploit the vulnerabilities by getting the victim to open a specially crafted HTML page.

Earlier this year, the researcher identified a similar insecure intent URI implementation flaw in Mercury Browser for Android. He also discovered the password users could set to protect Mercury, and OAuth tokens for Box file sharing accounts ended up stored insecurely.

Since these vulnerabilities remain unfixed, Rotlogix suggested Android users to utilize other web browsers.