CVE-2012-2136 in Linux
Summary
by MITRE
The sock_alloc_send_pskb function in net/core/sock.c in the Linux kernel before 3.4.5 does not properly validate a certain length value, which allows local users to cause a denial of service (heap-based buffer overflow and system crash) or possibly gain privileges by leveraging access to a TUN/TAP device.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-2136 represents a critical heap-based buffer overflow in the Linux kernel's networking subsystem that affects versions prior to 3.4.5. This flaw exists within the sock_alloc_send_pskb function located in the net/core/sock.c file, which is responsible for allocating packet socket buffers for network communication. The vulnerability specifically arises from inadequate validation of length parameters during packet buffer allocation operations, creating a scenario where malicious local users can exploit this weakness through controlled access to TUN/TAP network interfaces.
The technical exploitation of this vulnerability occurs when a local attacker with access to a TUN/TAP device can manipulate the length parameter passed to the sock_alloc_send_pskb function. This manipulation results in a heap-based buffer overflow that can corrupt adjacent memory regions and ultimately lead to system instability or complete system crashes. The vulnerability's impact extends beyond simple denial of service as it potentially allows privilege escalation, enabling attackers to gain elevated system privileges through carefully crafted packet data manipulation. The heap overflow occurs because the kernel fails to properly validate input parameters before using them to allocate memory buffers, creating a classic buffer overflow scenario in kernel space.
The operational impact of CVE-2012-2136 is significant for systems running affected Linux kernel versions, particularly those that utilize TUN/TAP virtual network interfaces for various networking operations including VPN implementations, network monitoring tools, or containerization environments. Local users with access to TUN/TAP devices can leverage this vulnerability to either crash the system entirely or potentially escalate their privileges to root level access, making it a serious concern for system administrators and security professionals. The vulnerability's exploitation requires local access and TUN/TAP device permissions, but the potential for privilege escalation means that even limited local access can result in complete system compromise.
Security mitigations for this vulnerability primarily involve upgrading to Linux kernel version 3.4.5 or later, which includes the necessary patches to properly validate length parameters in the sock_alloc_send_pskb function. System administrators should also implement strict access controls for TUN/TAP devices to limit local user access and reduce the attack surface. Additionally, monitoring for unusual network activity or system crashes that might indicate exploitation attempts can provide early detection of potential abuse. This vulnerability aligns with CWE-121 for heap-based buffer overflow and relates to ATT&CK technique T1068 for privilege escalation through local exploitation. Organizations should prioritize patch management to address this vulnerability and ensure that all systems running affected kernel versions are updated to prevent potential exploitation and maintain overall system security posture.