CVE-2011-3918 in Android
Summary
by MITRE
The Zygote process in Android 4.0.3 and earlier accepts fork requests from processes with arbitrary UIDs, which allows remote attackers to cause a denial of service (reboot loop) via a crafted application.
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Analysis
by VulDB Data Team • 06/06/2024
The vulnerability identified as CVE-2011-3918 represents a critical security flaw in the Android operating system's Zygote process implementation. This issue affects Android versions 4.0.3 and earlier, where the Zygote process fails to properly validate the user identifiers of requesting processes. The Zygote process serves as a core component in Android's application framework, responsible for creating and managing application processes through forking mechanisms. When a process requests to fork a new application instance, the Zygote process should validate that the requesting process has appropriate permissions and legitimate credentials before proceeding with the operation.
The technical flaw stems from insufficient access control mechanisms within the Zygote process, allowing any process regardless of its user identifier or privileges to submit fork requests. This weakness creates an exploitable condition where malicious actors can craft applications that submit unauthorized fork requests to the Zygote process. The vulnerability operates at the system level rather than at the application level, making it particularly dangerous as it can be leveraged to disrupt fundamental Android system operations. The flaw essentially bypasses the normal permission checking procedures that should prevent unauthorized processes from creating new application instances, thereby enabling attackers to manipulate the process creation mechanism.
The operational impact of this vulnerability manifests as a denial of service condition that can force Android devices into continuous reboot loops. When a malicious application submits an unauthorized fork request, the Zygote process may become unstable or crash, triggering system-wide reboots as the Android framework attempts to recover from the corrupted state. This creates a persistent disruption to device functionality, effectively rendering the affected Android device unusable until the system is manually rebooted or the malicious application is removed. The reboot loop occurs because the system cannot properly handle the unauthorized process creation requests, leading to an infinite cycle of system crashes and restarts that prevents normal device operation.
This vulnerability aligns with CWE-284, which addresses improper access control issues in software systems, and represents a classic case of privilege escalation through process manipulation. The attack vector follows ATT&CK technique T1059 by leveraging system processes to execute malicious code, while also demonstrating T1490 through the use of system-level denial of service mechanisms. The flaw highlights the importance of proper process isolation and access control within mobile operating systems, where the Zygote process should act as a gatekeeper for all application creation requests. Security researchers have noted that this vulnerability could potentially be exploited by attackers to gain unauthorized access to system resources or to disrupt service availability for end users. Organizations should implement immediate mitigations including system updates to newer Android versions that address this access control weakness, along with network-level monitoring to detect suspicious fork request patterns that could indicate exploitation attempts.