CVE-2016-8632 in Linux
Summary
by MITRE • 01/25/2023
The tipc_msg_build function in net/tipc/msg.c in the Linux kernel through 4.8.11 does not validate the relationship between the minimum fragment length and the maximum packet size, which allows local users to gain privileges or cause a denial of service (heap-based buffer overflow) by leveraging the CAP_NET_ADMIN capability.
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Analysis
by VulDB Data Team • 01/25/2023
The CVE-2016-8632 vulnerability resides within the Linux kernel's TIPC (Transparent Inter-Process Communication) protocol implementation, specifically in the tipc_msg_build function located in net/tipc/msg.c. This flaw represents a critical security issue that affects Linux kernel versions through 4.8.11, where the kernel fails to properly validate the relationship between minimum fragment length and maximum packet size parameters. The vulnerability is particularly concerning because it operates within the kernel space, where unauthorized privilege escalation can occur, potentially leading to complete system compromise.
The technical flaw manifests as a heap-based buffer overflow condition that occurs when the TIPC messaging subsystem processes network packets. The tipc_msg_build function does not adequately validate the correlation between fragment size constraints and maximum packet boundaries, creating a scenario where malicious input can cause memory corruption. This validation failure allows an attacker with the CAP_NET_ADMIN capability to craft specially formatted network packets that trigger the buffer overflow. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though the actual manifestation occurs in heap memory management due to improper bounds checking.
The operational impact of this vulnerability is significant for systems running affected Linux kernels, particularly those utilizing TIPC networking protocols or systems where users possess CAP_NET_ADMIN privileges. Local attackers with this capability can exploit the vulnerability to either escalate privileges to root level access or cause a system denial of service through kernel memory corruption. The heap-based buffer overflow can lead to unpredictable behavior including system crashes, memory corruption, or potential privilege escalation that could allow attackers to execute arbitrary code with kernel-level privileges. This makes the vulnerability particularly dangerous in multi-user environments or systems where network administration capabilities are granted to non-privileged users.
Mitigation strategies for CVE-2016-8632 include immediate kernel updates to versions that contain the patched TIPC implementation, which addresses the missing validation checks in the tipc_msg_build function. System administrators should also implement network segmentation to limit access to TIPC services and reduce the attack surface. Additionally, monitoring for unusual network traffic patterns that might indicate exploitation attempts can provide early detection of potential attacks. The vulnerability aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1499 which covers 'Endpoint Denial of Service', making it a critical concern for enterprise security teams managing Linux-based infrastructure. Organizations should also consider implementing privilege separation policies to minimize the risk of CAP_NET_ADMIN capability exposure and ensure that only trusted users have access to these powerful network administration privileges.