CVE-2012-4013 in KUNAI Browser for Remote Service
Summary
by MITRE
The WebView class in the Cybozu KUNAI Browser for Remote Service application beta for Android allows remote attackers to execute arbitrary JavaScript code, and obtain sensitive information, via a crafted application that places this code into a local file associated with a file: URL.
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Analysis
by VulDB Data Team • 02/06/2018
The CVE-2012-4013 vulnerability resides within the WebView component of the Cybozu KUNAI Browser for Remote Service application beta for Android, representing a critical security flaw that enables remote code execution through malicious JavaScript injection. This vulnerability specifically targets the browser's handling of file:// URLs and local file associations, creating an attack vector where remote adversaries can craft malicious applications to embed arbitrary JavaScript code within local files. The flaw demonstrates a fundamental failure in input validation and security boundary enforcement within the Android WebView implementation, allowing attackers to bypass normal security restrictions that should prevent remote code execution from local file sources.
The technical implementation of this vulnerability stems from improper handling of file:// URL schemes within the WebView component, where the application fails to adequately sanitize or restrict JavaScript execution when processing local files referenced through these URLs. When a malicious application places JavaScript code into a local file that is subsequently accessed via a file: URL, the WebView component executes this code without proper security context validation. This behavior directly violates security principles established in the OWASP Mobile Top 10 and aligns with CWE-94, which describes weaknesses in the execution of code from external sources. The vulnerability essentially creates a sandbox escape scenario where remote attackers can leverage local file access to execute arbitrary JavaScript, potentially leading to full system compromise.
The operational impact of CVE-2012-4013 extends beyond simple code execution, as it enables attackers to obtain sensitive information from the affected Android device. This includes access to local storage, browser cookies, cached data, and potentially sensitive user information stored within the application's context. The vulnerability affects users of the Cybozu KUNAI Browser for Remote Service application, which likely operates in enterprise environments where sensitive data processing occurs. Attackers can exploit this vulnerability through social engineering campaigns or by compromising applications that interact with the vulnerable browser component, making it particularly dangerous in corporate environments where the browser handles confidential business data. The attack requires minimal privileges and can be executed remotely, making it an attractive target for threat actors seeking persistent access to enterprise systems.
Mitigation strategies for CVE-2012-4013 should focus on immediate application updates and security configuration hardening. Organizations should implement strict WebView security policies that disable JavaScript execution for file:// URLs or enforce proper security context validation. The recommended approach includes updating to the latest version of the Cybozu KUNAI Browser application where the vulnerability has been patched, implementing network-level controls to restrict access to potentially malicious file:// URL schemes, and configuring application security policies that limit file access permissions. Security teams should also consider implementing mobile device management solutions that can monitor and control WebView behavior, as well as establish network segmentation to limit the potential impact of successful exploitation. This vulnerability aligns with ATT&CK technique T1059.007 for JavaScript execution and T1071.004 for application layer protocols, making it relevant to both endpoint and network security monitoring efforts.