Chrome for Android - Android APIs exposed to JavaScript

CVE Number: CVE-2012-4907
Title: Chrome for Android - Android APIs exposed to JavaScript
Affected Software: Confirmed on Chrome for Android v18.0.1025123
Credit: Takeshi Terada
Issue Status: v18.0.1025308 was released which fixes this vulnerability

Overview:
By abusing Java objects exposed to JavaScript, malicious Web pages can execute
arbitrary commands on Chrome for Android, if the accessibility setting of the
device is enabled.

Details:
Chrome for Android (v18.0.1025123) is prone to remote command execution
vulnerability. When a Chrome user visits a malicious Web page, the JavaScript
in the page can execute arbitrary commands (Java methods) in the context of
Chrome app.

Only users who have enabled device's accessibility setting are affected.
Accessibility setting is for those who have visual or physical limitations,
and is disabled by default. It is enabled by some apps such as TalkBack,
ClockBack and so on.

The root cause of the issue is:

1. Chrome automatically exposes some Java objects (e.g. "accessibility")
   to JavaScript if the device's accessibility setting is enabled.

2. And JavaScript is allowed to gain access to Java's ClassLoader via
   Java objects exposed to JavaScript.

Proof of Concept:
At present I do not have plans to disclose PoC for this issue.

Timeline:
2012/07/08 Reported to Google security team.
2012/09/12 Vender announced v18.0.1025308
2013/01/07 Disclosure of this advisory

Recommendation:
Upgrade to the latest version.

Reference:
http://googlechromereleases.blogspot.jp/2012/09/chrome-for-android-update.html
https://code.google.com/p/chromium/issues/detail?id=144813

Note:
The idea of this attack came from below Web page (Japanese).
http://www.kanasansoft.com/weblab/2012/04/webview_addjavascriptinterface_of_android_is_dangerous.html