CVE-2024-30088

CVE-2024-30088: Windows Kernel Time-of-Check Time-of-Use Race Condition Enabling Local Privilege Escalation

AI-generated analysis based on the vulnerability data on this page.

Summary

CVE-2024-30088 is a privilege-escalation vulnerability in the Windows kernel. A low-privileged local attacker can exploit a race condition to gain elevated privileges. Microsoft has patched this flaw; CISA added it to the Known Exploited Vulnerabilities (KEV) catalog on 15 October 2024, and the EU Cybersecurity Agency lists it as actively exploited since the same date.

Background

The vulnerability resides in a Windows kernel component where resource-state validation and subsequent use are not performed atomically. This class of issue is notoriously difficult to detect in code review because the vulnerable window may be extremely narrow and dependent on system scheduling. Windows kernel-mode code is trusted to enforce security boundaries between user sessions and privilege levels; a flaw here undermines that trust.

Root Cause

The underlying weakness is CWE-367: Time-of-Check Time-of-Use (TOCTOU) Race Condition. The kernel validates a resource property (for example, a handle or pointer) and then operates on that resource in a separate step. If an attacker can change the resource between the check and the use, the kernel may operate on attacker-controlled data. In this case, the race condition leads to an out-of-bounds or type-confusion scenario that the attacker leverages to elevate privileges.

Impact

Microsoft assigned this vulnerability a CVSS v3.1 score of 7.0 (HIGH) with the vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

• Attack Vector (AV): Local — The attacker must already have local access to the system.
• Attack Complexity (AC): High — Successful exploitation requires winning a race condition, which is non-trivial.
• Privileges Required (PR): Low — The attacker needs only a low-privileged local account.
• User Interaction (UI): None — No user action is needed.
• Scope (S): Unchanged — The vulnerable component does not impact resources beyond its security scope.
• Confidentiality, Integrity, and Availability (C/I/A): High — Successful exploitation grants the attacker complete control over the affected system.

The EPSS score is 0.68202 (99.243rd percentile), indicating a very high probability of active exploitation in the wild.

Exploitation Walkthrough

Ethics Notice: The following description is provided for defensive and detection purposes only. It describes the conceptual attack path without providing weaponized code.

An attacker with low-privileged local access prepares a multi-threaded execution environment. One thread repeatedly triggers the vulnerable kernel path while another thread manipulates the shared resource (for example, swapping a handle or rewriting a structure in user memory mapped into the kernel). The goal is to land the race window such that the kernel dereferences or operates on attacker-controlled data. Because the vulnerability is in kernel mode, successful exploitation typically yields execution in ring 0, allowing the attacker to overwrite process tokens and escalate to SYSTEM. The high attack-complexity rating reflects the number of attempts and precise timing required, not impossibility — the KEV and EU exploitation confirmations prove it is being achieved.

Affected and Patched Versions

Microsoft has confirmed that the following product lines are affected:

• Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
• Windows 11 (versions 21H2, 22H2, 23H2)
• Windows Server 2016
• Windows Server 2019
• Windows Server 2022 (including 23H2)

Exact patched build numbers are available in the Microsoft Security Response Center (MSRC) advisory. Organizations should verify they are running a build released on or after the June 2024 Patch Tuesday cycle.

Remediation

1. Apply the security update from Microsoft as soon as possible. This vulnerability is being actively exploited; delay increases risk.
2. Enable automatic updates for Windows systems to reduce patch lag.
3. Apply the principle of least privilege — restrict local interactive logon to only those users who require it.
4. Enable Credential Guard and other Windows hardening features to limit the value of SYSTEM-level compromise.
5. Review and restrict execution of untrusted code on endpoints to reduce the attack surface for low-privileged initial access.

Detection

• Monitor for unexpected privilege-escalation events (e.g., processes running as SYSTEM spawned from low-integrity contexts).
• Use ETW (Event Tracing for Windows) telemetry to capture kernel object-handle manipulations around the vulnerable component.
• Look for suspicious multi-threaded processes exhibiting high CPU in kernel mode combined with repeated system-call patterns.
• Correlate endpoint telemetry with the CISA KEV and EUVD-2024-28025 entries to prioritize alerts.

Assessment

This vulnerability is a textbook example of why TOCTOU flaws in kernel code are so dangerous: a single scheduling coincidence can collapse the entire system security boundary. The EPSS score of 0.68 and confirmed presence on both the CISA KEV catalog and the EU exploited-vulnerabilities list make this a clear patch-now priority. Two lessons stand out:

1. Atomic operations matter. Validation and use should occur within a single atomic context whenever feasible; where that is impossible, defensive copying or reference counting should be employed.
2. Patch velocity is a security control. The gap between patch release and confirmed in-the-wild exploitation here was only months; organizations with sluggish patching cycles were exposed to a known, actively exploited high-impact vulnerability.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-30088
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-30088