CVE-2016-3135 in Linux
Summary
by MITRE • 01/25/2023
Integer overflow in the xt_alloc_table_info function in net/netfilter/x_tables.c in the Linux kernel through 4.5.2 on 32-bit platforms allows local users to gain privileges or cause a denial of service (heap memory corruption) via an IPT_SO_SET_REPLACE setsockopt call.
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Analysis
by VulDB Data Team • 10/18/2024
The vulnerability identified as CVE-2016-3135 represents a critical integer overflow condition within the Linux kernel's netfilter subsystem, specifically affecting 32-bit platforms running kernel versions through 4.5.2. This flaw exists in the xt_alloc_table_info function located in net/netfilter/x_tables.c, where improper handling of integer values during table allocation operations creates a pathway for malicious exploitation. The vulnerability manifests when a local user executes an IPT_SO_SET_REPLACE setsockopt call, which is part of the iptables socket interface used for configuring netfilter packet filtering rules. The integer overflow occurs during memory allocation calculations, leading to heap memory corruption that can be leveraged for privilege escalation or system instability.
The technical implementation of this vulnerability stems from the kernel's failure to properly validate input parameters when processing netfilter table replacement operations. When a user-space application attempts to replace an existing iptables table using the IPT_SO_SET_REPLACE socket option, the kernel calculates the required memory allocation based on user-provided table dimensions. In 32-bit environments, the integer overflow occurs when the calculated memory requirements exceed the maximum value that can be represented by a 32-bit signed integer, causing the allocation size to wrap around to a much smaller value. This results in insufficient memory being allocated for the actual table data, creating heap corruption that can be exploited to execute arbitrary code with kernel privileges. The flaw aligns with CWE-190, Integer Overflow or Wraparound, and specifically demonstrates how improper integer handling in kernel space can lead to severe security consequences.
The operational impact of CVE-2016-3135 extends beyond simple denial of service to encompass full privilege escalation capabilities, making it particularly dangerous for systems running vulnerable kernel versions. Local users who can execute setsockopt calls with appropriate permissions can exploit this vulnerability to escalate their privileges from unprivileged user level to root access, effectively compromising the entire system. The heap corruption resulting from the integer overflow can be manipulated to overwrite critical kernel data structures or function pointers, enabling code execution in kernel space. Additionally, the vulnerability can be used to cause system crashes or denial of service conditions, making it a significant threat to system stability and availability. This aligns with ATT&CK technique T1068, Exploitation for Privilege Escalation, and demonstrates how kernel-level vulnerabilities can be leveraged for comprehensive system compromise.
Mitigation strategies for CVE-2016-3135 focus primarily on kernel version updates and system hardening measures. The most effective solution involves upgrading to Linux kernel versions 4.6 or later, where the integer overflow has been corrected through proper input validation and bounds checking in the xt_alloc_table_info function. System administrators should also implement strict access controls for setsockopt operations and monitor for unauthorized use of netfilter socket options. Additional mitigations include disabling unnecessary netfilter functionality when not required, implementing proper user privilege separation, and applying kernel lockdown mechanisms where available. The vulnerability highlights the importance of robust input validation in kernel space operations and demonstrates how seemingly minor integer handling flaws can result in catastrophic security consequences. Organizations should prioritize patch management for kernel components and conduct regular security assessments of their kernel configurations to prevent exploitation of similar vulnerabilities.