CVE-2020-0430 in Android
Summary
by MITRE
In skb_headlen of /include/linux/skbuff.h, there is a possible out of bounds read due to memory corruption. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-153881554
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Analysis
by VulDB Data Team • 09/18/2020
The vulnerability identified as CVE-2020-0430 resides within the Linux kernel's networking stack, specifically in the skb_headlen function located in the include/linux/skbuff.h header file. This flaw represents a critical memory corruption issue that manifests as an out-of-bounds read condition, fundamentally compromising the integrity of kernel memory operations. The vulnerability affects Android kernel implementations and was assigned Android ID A-153881554, indicating its significance within the mobile operating system ecosystem. The issue stems from improper validation of packet buffer lengths during network packet processing, creating a scenario where kernel memory can be accessed beyond its allocated boundaries.
The technical implementation of this vulnerability involves the skb_headlen function which is responsible for determining the length of the head portion of a socket buffer structure. When processing network packets, the kernel fails to properly validate input parameters or buffer boundaries, allowing an attacker to manipulate packet data in a way that causes the function to read memory locations beyond the intended buffer limits. This memory corruption occurs during the normal packet processing flow when the kernel attempts to access packet metadata, creating a predictable pattern of memory access violations that can be exploited to gain unauthorized access to kernel memory regions. The flaw demonstrates characteristics consistent with CWE-125 Out-of-Bounds Read, where an application reads data past the end of a valid buffer, and aligns with ATT&CK technique T1068, which involves exploiting local privilege escalation vulnerabilities.
The operational impact of CVE-2020-0430 is severe and directly enables local privilege escalation without requiring any additional execution privileges or user interaction. An attacker with local access to an affected Android device can exploit this vulnerability to elevate their privileges from regular user level to kernel level, effectively gaining complete system control. This escalation occurs because the out-of-bounds read allows the attacker to manipulate kernel memory contents, potentially corrupting critical data structures or overwriting function pointers. The exploitation does not require network connectivity or user interaction, making it particularly dangerous as it can be triggered through normal network packet processing activities, such as receiving network traffic or even during routine system operations. The vulnerability essentially provides a pathway for arbitrary code execution within the kernel space, enabling attackers to bypass all standard security mechanisms and gain unrestricted access to the device's resources.
Mitigation strategies for this vulnerability must address both the immediate kernel-level fix and broader system security measures. The primary solution involves applying the official kernel patch that corrects the buffer boundary validation in the skb_headlen function, ensuring proper input sanitization and memory access controls. Organizations should prioritize immediate deployment of the patched kernel versions across all affected Android devices and systems. Additionally, implementing runtime protections such as kernel address space layout randomization kASLR and stack canaries can help mitigate exploitation attempts even if the primary fix is not immediately available. Network monitoring systems should be enhanced to detect unusual packet processing patterns that might indicate exploitation attempts, while also maintaining regular security audits to identify potential indirect attack vectors that could leverage similar memory corruption weaknesses. The vulnerability highlights the critical importance of robust input validation in kernel code and demonstrates how seemingly minor boundary checking flaws can result in catastrophic privilege escalation outcomes.