CVE-2018-8611
Microsoft Windows Kernel Privilege Escalation Vulnerability
Description
CVE-2018-8611 is a privilege escalation vulnerability in the Microsoft Windows kernel caused by improper handling of objects in memory. A local attacker who has already gained code execution on the system can exploit this flaw to escalate their privileges from a standard user to SYSTEM level, gaining complete control over the affected Windows machine. This vulnerability was actively exploited as a zero-day before Microsoft released a patch, and CISA has confirmed exploitation by including it in the Known Exploited Vulnerabilities catalog. With an EPSS percentile of 94.8%, CVE-2018-8611 represents a high-priority target for remediation.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 10 1607 | - |
| microsoft | windows 10 1703 | - |
| microsoft | windows 10 1709 | - |
| microsoft | windows 10 1803 | - |
| microsoft | windows 10 1809 | - |
| microsoft | windows 7 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows server 2016 | - |
| microsoft | windows server 2019 | - |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- http://www.securityfocus.com/bid/106082(Third Party Advisory, VDB Entry)
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8611(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8611(US Government Resource)
Weakness Type
Since no specific CWE has been assigned to CVE-2018-8611, the underlying weakness type remains formally unspecified. The vulnerability involves improper object handling in Windows kernel memory, which typically indicates a use-after-free, type confusion, or integer overflow condition in kernel-mode code. When the kernel fails to properly track and validate memory objects, an attacker can manipulate these objects to corrupt kernel data structures and redirect execution flow to achieve privilege escalation.
Impact Analysis
CVE-2018-8611 enables local privilege escalation from any user-level process to SYSTEM privileges on affected Windows systems. The vulnerability requires local access, meaning the attacker must already have the ability to execute code on the target system, but no special privileges are needed beyond basic user-level access. Once exploited, the attacker gains SYSTEM-level control, which provides unrestricted access to all system resources, the ability to install rootkits, create administrative accounts, access all user data and credentials, and disable security software. The Windows kernel vulnerability is particularly dangerous because it affects all Windows processes regardless of their individual security settings or sandbox configurations. The EPSS percentile of 94.8% reflects sustained exploitation activity, and the vulnerability's history as a zero-day confirms it was used in targeted attacks before a patch was available.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2018-8611 by including it in the Known Exploited Vulnerabilities catalog with a remediation deadline of June 14, 2022. CVE-2018-8611 was originally discovered as a zero-day vulnerability being actively exploited in targeted attacks before Microsoft released a security update in December 2018. The EPSS percentile of 94.8% confirms ongoing exploitation interest. Windows kernel privilege escalation vulnerabilities are extremely valuable to attackers as they provide a universal escalation path from any user-level compromise to full SYSTEM control, making them a key component of advanced attack chains.
Remediation
- Apply the Microsoft security update that addresses CVE-2018-8611. CISA's required action is to apply updates per vendor instructions. The fix was released as part of the December 2018 Patch Tuesday.
- Ensure Windows Update is configured to automatically install security updates, and verify that the specific update addressing this vulnerability has been applied across all Windows endpoints.
- Implement kernel exploitation mitigations such as Virtualization-Based Security (VBS) and Hypervisor-Protected Code Integrity (HVCI), which can limit the impact of kernel memory corruption vulnerabilities.
- Deploy endpoint detection and response (EDR) solutions capable of detecting kernel exploitation attempts, including suspicious system call patterns and anomalous privilege transitions.
- Apply the principle of least privilege to limit the number of user accounts and processes that could serve as the initial access point for exploitation, reducing the overall attack surface for local privilege escalation.
Technical Details
CVE-2018-8611 targets the Windows kernel's memory object handling mechanism. The kernel manages a complex set of objects in kernel-mode memory for resources such as processes, threads, files, and synchronization primitives. When these objects are not properly validated, tracked, or cleaned up during their lifecycle, memory corruption can occur. The vulnerability allows a local attacker to trigger an improper memory operation that corrupts kernel data structures, which can then be leveraged to overwrite critical kernel pointers such as token objects or function pointers. By manipulating these structures, the attacker can elevate their process token from a standard user to SYSTEM, gaining unrestricted access to the operating system. The attack requires local code execution but operates against the kernel itself, bypassing all user-mode security controls, application sandboxes, and mandatory integrity controls. The fact that this was exploited as a zero-day indicates that sophisticated threat actors developed reliable exploitation techniques before the vulnerability was publicly known.
Frequently Asked Questions
Is CVE-2018-8611 being actively exploited?
Yes, CVE-2018-8611 was actively exploited as a zero-day vulnerability before Microsoft released a patch in December 2018. CISA has added it to the Known Exploited Vulnerabilities catalog. The EPSS percentile of 94.8% confirms high exploitation probability.
What products are affected by CVE-2018-8611?
CVE-2018-8611 affects the Microsoft Windows kernel across multiple Windows versions. All Windows systems that were current at the time of the December 2018 patch release should be considered potentially affected until the security update is applied.
How do I fix CVE-2018-8611?
Apply the Microsoft security update released in December 2018 that addresses CVE-2018-8611. Verify the update has been applied across all Windows endpoints through Windows Update or enterprise patch management tools.
How severe is CVE-2018-8611?
CVE-2018-8611 is a Windows kernel privilege escalation vulnerability with an EPSS percentile of 94.8% that was exploited as a zero-day. While it requires local access, it allows escalation to SYSTEM privileges, providing complete control over the affected system. Its zero-day exploitation history and CISA KEV inclusion confirm it as a high-severity vulnerability.
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