CVE-2021-38784 in R818 SoC Android Q SDK
Summary
by MITRE • 01/18/2022
There is a NULL pointer dereference in the syscall open_exec function of Allwinner R818 SoC Android Q SDK V1.0 that could executable a malicious file to cause a system crash.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability identified as CVE-2021-38784 represents a critical NULL pointer dereference flaw within the syscall open_exec function of the Allwinner R818 System-on-Chip implementation in the Android Q SDK version 1.0. This issue resides in the kernel-level system call handling mechanism that governs executable file access operations, specifically affecting devices utilizing the Allwinner R818 SoC architecture. The vulnerability manifests when the system attempts to process executable file operations through the open_exec syscall, creating a scenario where a NULL pointer reference can be dereferenced without proper validation, leading to immediate system termination.
The technical flaw stems from inadequate input validation within the kernel's file execution handling subsystem, where the open_exec function fails to properly check for NULL pointer conditions before attempting to access memory locations. This particular vulnerability falls under CWE-476 which specifically addresses NULL Pointer Dereference conditions in software implementations. When malicious code attempts to execute a specially crafted file through the vulnerable syscall interface, the system's execution flow encounters a NULL reference that cannot be resolved, resulting in an immediate system crash or reboot. The flaw operates at the kernel level, making it particularly dangerous as it can be exploited to cause denial-of-service conditions without requiring elevated privileges.
The operational impact of this vulnerability extends beyond simple system instability, as it provides attackers with a reliable method to induce system crashes on affected devices. This capability can be leveraged for various malicious purposes including persistent denial-of-service attacks that could disrupt device functionality, or as part of broader exploitation campaigns targeting embedded systems and IoT devices that utilize the Allwinner R818 SoC. The vulnerability affects Android Q implementations specifically, indicating that devices running this version of the Android operating system are at risk when they incorporate the vulnerable SDK components. From an adversarial perspective, this flaw aligns with ATT&CK technique T1499.004 which involves network disruption and system resource exhaustion through denial-of-service mechanisms.
Mitigation strategies for CVE-2021-38784 should prioritize immediate firmware updates from device manufacturers that address the specific NULL pointer dereference in the open_exec syscall implementation. System administrators should implement comprehensive patch management protocols to ensure all affected devices receive timely security updates. Additionally, monitoring systems should be deployed to detect anomalous execution patterns that might indicate exploitation attempts, particularly around file execution and syscall operations. Network segmentation and access controls should be reinforced to limit potential attack surfaces, while device vendors should consider implementing additional kernel-level protections against malformed executable file processing. The vulnerability demonstrates the importance of thorough input validation and pointer safety checks in kernel-space code, emphasizing that even seemingly simple system calls can contain critical flaws that compromise entire system stability and security posture.