CVE-2016-0040
Microsoft Windows Kernel Privilege Escalation Vulnerability
Description
CVE-2016-0040 is a privilege escalation vulnerability (CWE-269) in the Microsoft Windows kernel that allows a locally authenticated attacker to execute arbitrary code in kernel mode, gaining SYSTEM-level privileges. The vulnerability exists because the Windows kernel improperly handles objects in memory, enabling an attacker with standard user access to elevate their privileges to the highest level on the system. CISA has confirmed active exploitation and added CVE-2016-0040 to the Known Exploited Vulnerabilities catalog. With an EPSS score of 78.9%, this vulnerability presents a high-priority privilege escalation risk for unpatched Windows environments.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 7 | - |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows vista | - |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- http://www.securitytracker.com/id/1034985(Broken Link, Third Party Advisory, VDB Entry)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-014(Patch, Vendor Advisory)
- https://www.exploit-db.com/exploits/44586/(Exploit, Third Party Advisory, VDB Entry)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-0040(US Government Resource)
Weakness Type
CWE-269: Improper Privilege Management
CWE-269 describes a weakness where software fails to properly assign, modify, track, or verify privileges for an actor, enabling unauthorized privilege escalation. In CVE-2016-0040, the Windows kernel does not correctly manage privilege boundaries when handling certain memory objects, allowing a local attacker to bypass security controls and execute code with kernel-level privileges.
Learn more: CWE-269 — Improper Privilege Management
Impact Analysis
CVE-2016-0040 allows a locally authenticated attacker to execute code in kernel mode, which effectively grants SYSTEM-level privileges — the highest authority on a Windows system. While the attack vector requires local access, the impact is catastrophic: kernel-mode code execution enables complete operating system compromise, including the ability to disable all security mechanisms, install kernel-level rootkits, access any file or memory region, intercept all system calls, and persist through reboots. This vulnerability is particularly valuable in attack chains where an attacker has gained initial user-level access through phishing or another vector and needs to escalate privileges to achieve full system control. The EPSS score of 78.9% reflects substantial real-world exploitation activity.
Exploit Maturity
CVE-2016-0040 is confirmed as actively exploited in the wild by CISA and is listed in the Known Exploited Vulnerabilities catalog. The EPSS score of 78.9% indicates high real-world exploitation probability, and Windows kernel privilege escalation vulnerabilities are among the most sought-after primitives in both targeted attacks and commodity malware. Public exploit code and documentation for this vulnerability class are widely available, making integration into post-exploitation frameworks straightforward.
Remediation
- Apply the Microsoft security update MS16-014 (February 2016) to patch the Windows kernel vulnerability on all affected systems immediately.
- Implement the principle of least privilege for all user accounts to minimize the damage potential of privilege escalation exploits.
- Enable Credential Guard and virtualization-based security (VBS) on Windows 10 and later systems to provide hardware-level protection against kernel-level exploitation.
- Deploy endpoint detection and response (EDR) tools with kernel-level monitoring to detect suspicious privilege escalation patterns and anomalous kernel object access.
- Keep all Windows systems fully patched and on supported versions, as kernel privilege escalation vulnerabilities in end-of-life Windows versions will not receive additional security updates.
Technical Details
CVE-2016-0040 is a privilege escalation vulnerability (CWE-269) in the Windows kernel caused by improper handling of objects in memory. When the kernel processes certain system calls, it fails to properly validate or manage memory object references, allowing a local attacker to craft a malicious application that manipulates kernel memory structures to achieve arbitrary code execution in ring 0 (kernel mode). The exploitation typically involves creating carefully crafted memory layouts that trigger the vulnerable code path, then leveraging the resulting memory corruption to overwrite kernel data structures such as process token objects, effectively granting the attacker's process SYSTEM-level privileges. The attack requires local execution but no special privileges beyond standard user access.
Frequently Asked Questions
Is CVE-2016-0040 being actively exploited?
Yes. CVE-2016-0040 is confirmed as actively exploited in the wild by CISA and is listed in the Known Exploited Vulnerabilities catalog. The EPSS score of 78.9% reflects high real-world exploitation activity targeting Windows kernel privilege escalation.
What products are affected by CVE-2016-0040?
CVE-2016-0040 affects the Windows kernel across multiple Microsoft Windows versions, including Windows Vista, Windows 7, Windows 8.1, Windows Server 2008, and Windows Server 2012. Windows 10 may also be affected depending on the specific build.
How do I fix CVE-2016-0040?
Apply the Microsoft security update MS16-014 (February 2016) on all affected Windows systems. Enable Credential Guard and virtualization-based security where available, and implement least-privilege access controls.
How severe is CVE-2016-0040?
CVE-2016-0040 is a high-severity privilege escalation vulnerability that enables kernel-mode code execution from a standard user account. The EPSS score of 78.9% and CISA KEV listing confirm significant active exploitation, making it a critical priority for patch management.
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