CVE-2015-8543 in Linux
Summary
by MITRE
The networking implementation in the Linux kernel through 4.3.3, as used in Android and other products, does not validate protocol identifiers for certain protocol families, which allows local users to cause a denial of service (NULL function pointer dereference and system crash) or possibly gain privileges by leveraging CLONE_NEWUSER support to execute a crafted SOCK_RAW application.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/01/2022
The vulnerability identified as CVE-2015-8543 represents a critical flaw in the Linux kernel's networking subsystem that affects versions through 4.3.3 and has widespread implications across Android and other operating systems. This issue stems from insufficient validation of protocol identifiers within specific protocol families, creating a pathway for malicious exploitation that can result in system instability or privilege escalation. The vulnerability specifically impacts the kernel's handling of raw socket operations and demonstrates a fundamental weakness in the kernel's input validation mechanisms that govern network protocol processing.
The technical implementation of this vulnerability occurs within the kernel's networking layer where protocol identifiers are not properly validated for certain protocol families. When a local user leverages the CLONE_NEWUSER capability, they can execute a crafted SOCK_RAW application that exploits this validation gap. The flaw manifests as a NULL function pointer dereference, which occurs when the kernel attempts to invoke a function that has not been properly initialized or assigned. This type of vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is a common vector for denial of service attacks and can potentially be extended to privilege escalation scenarios. The combination of CLONE_NEWUSER support with raw socket manipulation creates a unique exploitation vector that bypasses normal security boundaries.
The operational impact of CVE-2015-8543 extends beyond simple denial of service to potentially enable privilege escalation, making it particularly dangerous in multi-user environments or when running on devices with varying security configurations. Local users who can execute code with sufficient privileges to utilize CLONE_NEWUSER can leverage this vulnerability to crash the system or gain elevated privileges, depending on the specific implementation details and system configuration. The vulnerability's potential for privilege escalation aligns with ATT&CK technique T1068 which covers 'Local Privilege Escalation' through kernel exploits. The impact is significant because it allows attackers to compromise system integrity and potentially gain unauthorized access to sensitive system resources, making it a prime target for both casual attackers and more sophisticated threat actors.
Mitigation strategies for CVE-2015-8543 should focus on both immediate patching and operational security measures. The primary solution involves updating to a patched kernel version that properly validates protocol identifiers for the affected protocol families. Organizations should also implement strict user privilege controls to limit the ability of untrusted users to utilize CLONE_NEWUSER capabilities, particularly in environments where this functionality might be exploited. Network segmentation and monitoring can help detect anomalous socket creation patterns that might indicate exploitation attempts. Additionally, system administrators should consider implementing kernel hardening measures such as disabling unnecessary protocol families or implementing stricter socket access controls to reduce the attack surface. The vulnerability demonstrates the importance of comprehensive input validation in kernel space and highlights the need for continuous security auditing of core operating system components.