CVE-2019-2045 in Android
Summary
by MITRE
In JSCallTyper of typer.cc, there is an out of bounds write due to an incorrect bounds check. This could lead to remote code execution in the proxy auto-config with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.1 Android-9 Android ID: A-117554758
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Analysis
by VulDB Data Team • 06/08/2020
The vulnerability identified as CVE-2019-2045 represents a critical out-of-bounds write flaw within the JavaScript engine's type system implementation in Android's web rendering framework. This issue resides in the JSCallTyper component of the typer.cc file, where an insufficient bounds check allows malicious code to write beyond allocated memory boundaries. The vulnerability specifically affects Android versions 7.0 through 9.0, making it a widespread concern across multiple Android releases that have been in production for several years. The flaw exists in the proxy auto-config functionality, which is typically used for automatic proxy configuration in web browsers and network applications. This particular implementation allows for remote code execution without requiring any additional privileges or user interaction, making it particularly dangerous as it can be exploited through network-based attacks without any user involvement.
The technical nature of this vulnerability stems from improper validation of array indices or memory access boundaries during JavaScript type inference operations. When the JavaScript engine processes certain code patterns, it incorrectly calculates or validates memory boundaries, leading to a situation where data can be written to memory locations beyond the intended array or buffer limits. This type of flaw typically falls under CWE-787: "Out-of-bounds Write" which is classified as a critical vulnerability in the Common Weakness Enumeration catalog. The vulnerability's classification as a remote code execution vector means that an attacker can potentially execute arbitrary code on a target device simply by delivering malicious content through a web browser or network connection. The lack of user interaction requirement makes this vulnerability particularly concerning for mobile environments where users may encounter malicious content while browsing the web or using network services.
The operational impact of CVE-2019-2045 extends beyond simple exploitation as it affects the core web rendering capabilities of Android devices, potentially allowing attackers to gain complete control over affected systems. Mobile devices running the affected Android versions become vulnerable to attacks that could result in data theft, persistent backdoor installation, or complete device compromise. The vulnerability's presence in the proxy auto-config functionality means that even simple web browsing activities could trigger exploitation, as many websites and services use proxy configuration mechanisms. This vulnerability aligns with ATT&CK technique T1059.007 for Windows and similar mobile attack patterns that involve code injection through browser-based exploits. The attack surface is significantly broadened because the vulnerability affects the underlying JavaScript engine that powers not just web browsers but also many mobile applications that utilize web rendering components, making this a systemic risk across the Android ecosystem.
Mitigation strategies for CVE-2019-2045 primarily involve applying the latest security patches and updates from Google, which would include the Android Security Bulletins containing fixes for this specific vulnerability. Organizations and users should prioritize immediate patching of all affected Android devices, as the vulnerability does not require user interaction for exploitation. Network administrators should consider implementing additional security controls such as web filtering solutions and proxy configurations that can detect and block malicious content before it reaches vulnerable devices. The vulnerability's nature as an out-of-bounds write also suggests that memory protection mechanisms like stack canaries, address space layout randomization, and data execution prevention could provide additional layers of defense. However, given that this is a fundamental flaw in the JavaScript engine's type system, the most effective mitigation remains the application of official security updates from the Android platform vendors. The vulnerability serves as a reminder of the importance of maintaining up-to-date mobile security implementations and the potential risks associated with complex JavaScript engines in mobile operating systems.