CVE-2016-7117 in Android
Summary
by MITRE • 01/25/2023
Use-after-free vulnerability in the __sys_recvmmsg function in net/socket.c in the Linux kernel before 4.5.2 allows remote attackers to execute arbitrary code via vectors involving a recvmmsg system call that is mishandled during error processing.
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Analysis
by VulDB Data Team • 01/25/2023
The CVE-2016-7117 vulnerability represents a critical use-after-free flaw in the Linux kernel's networking subsystem that was present in kernel versions prior to 4.5.2. This vulnerability specifically affects the __sys_recvmmsg function located in the net/socket.c file, which handles the recvmmsg system call for receiving messages from socket descriptors. The flaw occurs during error processing when the kernel fails to properly manage memory references, creating conditions where freed memory locations can be accessed by malicious actors. The vulnerability is classified under CWE-416 as a use-after-free condition, which is a well-known class of memory safety issues that can lead to arbitrary code execution and system compromise.
The technical exploitation of this vulnerability requires an attacker to trigger a recvmmsg system call with specific parameters that cause the kernel to enter an error handling path. During this error processing, the kernel's memory management routines fail to properly invalidate pointers to freed memory structures, allowing subsequent operations to access this already-released memory. The attacker can leverage this condition to overwrite critical kernel memory locations, potentially leading to privilege escalation from user-level processes to kernel-level execution. This represents a classic remote code execution vector that can be exploited over network connections without requiring local access to the target system.
The operational impact of CVE-2016-7117 extends beyond simple code execution, as it provides attackers with the ability to gain full control over affected systems. The vulnerability affects systems running Linux kernel versions before 4.5.2, which includes many widely deployed server and desktop environments. Attackers can exploit this vulnerability to establish persistent backdoors, escalate privileges, or cause system crashes that result in denial of service. The remote nature of the attack means that systems can be compromised from outside the local network, making this vulnerability particularly dangerous for publicly accessible servers. This vulnerability aligns with ATT&CK technique T1068 which covers 'Local Privilege Escalation' and T1059 which covers 'Command and Scripting Interpreter' as attackers can leverage the kernel-level access to execute arbitrary commands.
Mitigation strategies for CVE-2016-7117 focus primarily on kernel version upgrades to 4.5.2 or later, which contain the necessary patches to address the memory management error in the recvmmsg system call handling. System administrators should prioritize updating their Linux kernels to the patched versions and verify that all network services are running on properly updated systems. Additional defensive measures include implementing network segmentation to limit exposure, monitoring for suspicious network activity related to socket operations, and applying kernel hardening configurations such as stack canaries and address space layout randomization. The vulnerability demonstrates the critical importance of maintaining up-to-date kernel versions and highlights the potential for memory safety issues to create severe security risks in operating system kernels. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and ensure that all systems are regularly patched against known vulnerabilities.