CVE-2016-9031 in SmartOS
Summary
by MITRE
An exploitable integer overflow exists in the Joyent SmartOS 20161110T013148Z Hyprlofs file system. The vulnerability is present in the Ioctl system call with the command HYPRLOFS_ADD_ENTRIES when dealing with 32-bit file systems. An attacker can craft an input that can cause a kernel panic and potentially be leveraged into a full privilege escalation vulnerability. This vulnerability is distinct from CVE-2016-8733.
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Analysis
by VulDB Data Team • 10/08/2022
The vulnerability identified as CVE-2016-9031 represents a critical integer overflow flaw within the Joyent SmartOS hypervisor filesystem implementation known as Hyprlofs. This issue specifically manifests in the Ioctl system call handling mechanism when processing the HYPRLOFS_ADD_ENTRIES command on 32-bit file system configurations. The flaw exists at the kernel level where input validation fails to properly handle boundary conditions, creating a scenario where maliciously crafted parameters can trigger unexpected behavior in the kernel memory management subsystem. The vulnerability demonstrates characteristics consistent with CWE-190, Integer Overflow or Wraparound, where arithmetic operations exceed the maximum representable value for the target data type, leading to unpredictable system states.
The technical exploitation of this vulnerability occurs through the manipulation of the Ioctl interface within the Hyprlofs filesystem driver. When the HYPRLOFS_ADD_ENTRIES command is invoked with specially crafted parameters, the kernel's handling of the input data causes integer overflow conditions that can result in memory corruption. The 32-bit file system context is particularly susceptible because the arithmetic operations involved in calculating buffer sizes or entry counts can exceed the maximum value that can be represented in 32-bit signed integers, causing wraparound behavior that leads to memory layout corruption. This type of vulnerability falls under the ATT&CK technique T1068, Exploitation for Privilege Escalation, as the kernel panic condition can be leveraged to gain elevated privileges within the operating system environment.
The operational impact of CVE-2016-9031 extends beyond simple system instability to potentially enable complete system compromise. A successful exploitation can cause immediate kernel panic conditions that result in system crashes or reboots, disrupting service availability. However, the more concerning aspect is the potential for privilege escalation, where an attacker could leverage the integer overflow to execute arbitrary code with kernel-level privileges. This would allow for complete control over the affected SmartOS system, enabling data exfiltration, persistent backdoor installation, or further lateral movement within network environments. The vulnerability's distinct nature from CVE-2016-8733 indicates that while both affect the Hyprlofs implementation, they represent different attack surfaces within the same filesystem driver, requiring separate mitigation approaches.
Mitigation strategies for this vulnerability should focus on immediate patching of the Joyent SmartOS kernel components and implementation of proper input validation mechanisms. System administrators should prioritize updating to patched versions of SmartOS that address the integer overflow conditions in the Hyprlofs driver. Additionally, monitoring for anomalous Ioctl system call patterns and implementing kernel hardening measures such as stack canaries and address space layout randomization can help detect or prevent exploitation attempts. The vulnerability highlights the importance of proper integer arithmetic validation in kernel space code and reinforces the need for comprehensive security testing of filesystem drivers, particularly those handling privileged operations through Ioctl interfaces. Organizations should also consider implementing network segmentation and privilege separation to limit the potential impact of successful exploitation attempts.