CVE-2026-79417

Executive Summary

CVE-2026-79417 is an improper access control vulnerability in the ArgusMonitor.sys kernel driver shipped with Argotronic eGbR ArgusMonitor version 7.4.02 and earlier. A local, low-privileged user can exploit a time-of-check-time-of-use (TOCTOU) race condition in the driver's IRP_MJ_CREATE handling to bypass device handle access restrictions and subsequently issue a crafted IOCTL 0x9C4024A8 request, resulting in a denial-of-service condition. The vulnerability is unpatched, no public proof-of-concept or exploit code is known, and no CVSS score or CWE identifier has been assigned by the vendor or NVD at the time of publication.

Technical Analysis

ArgusMonitor.sys is a Windows kernel-mode driver that exposes a device object to user-mode applications for hardware monitoring functionality. Access to this device object is normally gated by a security descriptor applied to the device handle, restricting which local users can open a handle and interact with the driver.

The vulnerability is a TOCTOU (Time-of-Check-Time-of-Use) condition that occurs within the IRP_MJ_CREATE dispatch path. In Windows kernel drivers that implement custom IRP_MJ_CREATE handlers, a driver may inspect caller identity or context at handle-open time — for example, verifying the requesting process's token or checking whether a device handle was opened with specific access rights — and then make an access-control decision. A TOCTOU flaw arises when the state checked at open time can be altered between the check and the subsequent use of that state, or when the check is performed against a resource that can be manipulated (e.g., via handle duplication, a symbolic link swap, or a concurrent request operating on the same object).

In this case, the race condition allows a local low-privileged caller to bypass the device handle access restrictions. By winning the race, the attacker obtains a usable handle to the device that would otherwise have been denied based on the caller's privilege level. With the handle in hand, the attacker can dispatch an IOCTL request with the control code 0x9C4024A8 to the driver.

The impact described is denial-of-service. Sending a crafted IOCTL 0x9C4024A8 request through the improperly granted handle triggers a fault condition in the driver (the exact nature — whether a null-pointer dereference, unchecked buffer access, or resource exhaustion — is not specified in the available data). Because the vulnerable code runs in kernel mode, a fault in the driver can cause a system crash (bugcheck) or otherwise render the system unavailable, rather than merely terminating the offending user process.

The attack is strictly local: it requires the ability to execute code on the target host as a low-privileged user and to open a handle to the vulnerable device and race the IRP_MJ_CREATE path. No remote vector is described.

Given the sparse technical detail available, the following specifics cannot be confirmed from the source data and are therefore not asserted: the exact synchronization primitive or object that is raced, the precise access-control check that is bypassed, the calling convention or expected input/output buffer layout of IOCTL 0x9C4024A8, and the exact fault produced. These gaps are noted to avoid over-specification.

Exploitation Scenarios

The following attack chain is inferred from the vulnerability class (local TOCTOU access-control bypass in a kernel driver) and the details explicitly provided in the description. No public PoC is available, and no exploit code, Nuclei template, or weaponized tooling is known.

1. Reconnaissance / target identification. The attacker has local access to a Windows host on which Argotronic eGbR ArgusMonitor 7.4.02 or earlier is installed. The attacker identifies the presence of the ArgusMonitor.sys kernel driver and its user-accessible device object. This can be done from a low-privileged user context by enumerating loaded drivers and device objects exposed by the driver.

2. Triggering the flaw class. The attacker repeatedly attempts to open a handle to the device via IRP_MJ_CREATE while racing the access-control check. The TOCTOU window means that if the attacker can alter or interleave state during the check-then-use sequence, the handle is granted despite the caller's low privilege. In practice this is implemented as a tight loop of concurrent CreateFile-style open operations and synchronization attempts designed to land in the vulnerable window. No specific API sequence beyond the IRP_MJ_CREATE path is claimed.

3. Payload / execution method. Once a handle is obtained through the bypassed access-control path, the attacker issues an IOCTL request using control code 0x9C4024A8 via the standard DeviceIoControl mechanism. The request is crafted to reach the vulnerable code path in the driver. The exact buffer contents required are not specified in the available data.

4. Post-exploitation impact. The crafted IOCTL 0x9C4024A8 request causes a denial-of-service condition on the affected host — potentially a kernel fault leading to a system crash or hang, or a driver-level failure that disrupts monitoring or dependent functionality. The described impact is availability-only; confidentiality and integrity impacts are not described.

No public proof-of-concept is available; the attack chain above is inferred from the vulnerability class and must be validated against a controlled lab instance of the affected product. The practical exploitability of a race-based TOCTOU depends on timing reliability, CPU scheduling, and the width of the race window, none of which are quantified in the source data.

Impact Assessment

The primary impact is to availability. A successful exploitation crashes or destabilizes the local system by triggering a fault in kernel-mode driver context. Because the flaw resides in a kernel driver, the consequences extend beyond the attacking process: a bugcheck terminates the entire operating system, disrupting all users and workloads on the host.

• Affected systems: Windows hosts running Argotronic eGbR ArgusMonitor 7.4.02 or earlier with the ArgusMonitor.sys driver loaded. The description does not state which Windows versions are supported by the product, so exact OS coverage is not asserted.
• Attack surface: Local only. Requires prior code execution as a low-privileged user on the target host.
• Blast radius: Single host per exploitation attempt. In managed fleets where ArgusMonitor is deployed for hardware monitoring on workstations or servers, the flaw provides an unprivileged local user a reliable way to force a reboot/crash, which can be used defensively (anti-forensics, disruption) or as part of a broader reliability-degradation attack.
• CVSS assessment: No CVSS score or vector was published by the vendor or NVD. The vector in the METADATA section (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H) is an analytical estimate consistent with a local, low-privilege, race-dependent availability-only flaw; it is not an authoritative score and should not be cited as such.
• Exploit maturity: Low. No PoC, no exploit code, no Nuclei template, and no CISA KEV listing. EPSS has not scored this CVE.
• Patch state: Unpatched with a patch confidence of 0/4 — no patch evidence from any tracked source.

Detection Guidance

Detection focuses on abnormal local interaction with the ArgusMonitor driver, anomalous handle-open behavior against its device object, and the crafted IOCTL control code 0x9C4024A8. Because exploitation is local, host-based telemetry (driver load, process-to-device handle operations, kernel crash events) is the most reliable detection surface; network rules below provide lower-fidelity coverage.

Sigma Rule

title: Potential CVE-2026-79417 ArgusMonitor.sys Access Control Bypass and IOCTL Abuse
id: 3f6a1c2e-9b74-4d21-8e55-argusmon79417
status: experimental
description: Detects local attempts to interact with the ArgusMonitor.sys driver device object and issue crafted IOCTL 0x9C4024A8 requests after a suspected TOCTOU access-control bypass.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-79417
author: Threat Intelligence
date: 2026/01/01
logsource:
  product: windows
  category: process_creation
detection:
  selection_img:
    - Image|endswith: '\ArgusMonitor.exe'
    - Image|endswith: '\ArgusMonitorService.exe'
  selection_susp:
    CommandLine|contains:
      - 'ArgusMonitor'
      - 'IOCTL'
      - '0x9C4024A8'
  condition: selection_img and selection_susp
fields:
  - Image
  - CommandLine
  - User
  - ParentImage
falsepositives:
  - Legitimate ArgusMonitor components issuing normal IOCTLs
level: medium
tags:
  - attack.privilege_escalation
  - attack.t1068
  - cve.2026.79417

YARA Rule

rule CVE_2026_79417_ArgusMonitor_IOCTL_Abuse
{
    meta:
        description = "Detects binaries/scripts referencing ArgusMonitor.sys IOCTL 0x9C4024A8 abuse related to CVE-2026-79417"
        author = "Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-79417"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $ioctl = { A8 24 40 9C }
        $drv1  = "ArgusMonitor.sys" ascii wide nocase
        $dev1  = "ArgusMonitor" ascii wide nocase
        $api1  = "DeviceIoControl" ascii
        $api2  = "CreateFile" ascii

    condition:
        uint16(0) == 0x5A4D and
        $ioctl and
        ( $drv1 or $dev1 ) and
        ( $api1 or $api2 )
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-79417 ArgusMonitor.sys IOCTL 0x9C4024A8 access-control bypass activity (local lateral artifact)"; flow:to_server; content:"|A8 24 40 9C|"; sid:90079417; rev:1; metadata:created_at 2026_01_01, cve CVE-2026-79417; classtype:attempted-dos;)

Note: exploitation of this CVE is local and does not traverse the network. The Suricata rule above is a low-fidelity artifact-matching rule for environments that forward serialized local IPC/IOCTL telemetry over the wire or that tunnel tooling traffic; it is not expected to fire on native local exploitation.

Elastic Detection

process where event.action == "start" and
  (
    process.name : ("ArgusMonitor.exe", "ArgusMonitorService.exe") or
    process.command_line : "*ArgusMonitor*" or
    process.command_line : "*9C4024A8*"
  ) and
  process.args_count > 0

Broader EQL targeting driver load followed by abnormal device handle operations:

sequence by host.id with maxspan=1m
  [ driver where event.action == "load" and driver.name : "ArgusMonitor.sys" ]
  [ process where event.action == "start" and process.command_line : "*ArgusMonitor*" ]

Splunk SPL Query

index=windows (source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="WinEventLog:System")
(EventCode=6 AND ImageLoaded="*ArgusMonitor.sys*")
OR (EventCode=1 AND (CommandLine="*ArgusMonitor*" OR CommandLine="*9C4024A8*"))
OR (EventCode=1001 AND Message="*ArgusMonitor*")
| stats count min(_time) as first_seen max(_time) as last_seen by host, user, Image, CommandLine, EventCode
| where count > 0
| sort - last_seen

Driver load (Sysmon EventID 6) correlates with ArgusMonitor.sys; BugCheck/System events (EventID 1001) capture availability-impact crashes consistent with the described denial-of-service.

Wazuh OSSEC Rule

<group name="windows,argusmonitor,cve-2026-79417,">
  <rule id="100717" level="8">
    <if_group>windows</if_group>
    <decoded_as>windows_eventchannel</decoded_as>
    <field name="win.system.eventID">^1001$</field>
    <field name="win.system.message">ArgusMonitor|0x9C4024A8</field>
    <description>CVE-2026-79417: possible ArgusMonitor.sys IOCTL 0x9C4024A8 abuse or driver crash</description>
    <mitre>
      <id>T1068</id>
    </mitre>
    <group>cve_2026_79417,</group>
  </rule>

  <rule id="100718" level="8">
    <if_group>windows</if_group>
    <decoded_as>windows_eventchannel</decoded_as>
    <field name="win.system.eventID">^6$</field>
    <field name="win.eventdata.imageLoaded">ArgusMonitor\.sys</field>
    <description>CVE-2026-79417: ArgusMonitor.sys kernel driver loaded</description>
    <group>cve_2026_79417,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch evidence from any tracked source; no vendor fix or workaround is documented as of this report.

1. Immediate mitigations

   • Restrict local interactive access to hosts where ArgusMonitor is deployed, limiting which accounts can log on locally. The flaw requires local low-privileged code execution, so reducing unprivileged local logon opportunities reduces exposure.
   • If ArgusMonitor is not operationally required, uninstall it or disable/stop the associated service and driver loading. Removal of the vulnerable ArgusMonitor.sys driver eliminates the attack surface.
   • Apply Windows driver-blocking controls (e.g., WDAC/AppLocker with a driver blocklist, or the Microsoft vulnerable driver blocklist mechanism) to prevent unmanaged loading of ArgusMonitor.sys if the product is not needed on a given class of hosts.
   • Monitor for and investigate unexpected kernel bugchecks/reboots on hosts running ArgusMonitor, as these may indicate exploitation attempts.

2. Patch / upgrade steps

   • No fixed version is currently identified. Monitor the Argotronic eGbR vendor channel and the NVD entry for CVE-2026-79417 for an updated release.
   • Until a fixed build is available, treat all versions "<= 7.4.02" as vulnerable and apply the mitigations above.
   • When a patch is released, upgrade to the vendor-designated fixed version and verify the driver file version on each endpoint.

3. Long-term hardening

   • Maintain an inventory of third-party kernel-mode drivers across the fleet and track their patch status; kernel drivers carry system-wide availability risk.
   • Enforce least privilege on endpoints to limit the low-privileged local execution the flaw depends on.
   • Require vendor disclosure of security fixes for kernel drivers as a procurement criterion, and prefer products with a responsive security patch cadence.
   • Enable and centrally collect kernel crashdump and driver-load telemetry to detect anomalous driver interaction and availability-impact events.

References

• NVD — CVE-2026-79417: https://nvd.nist.gov/vuln/detail/CVE-2026-79417
• Argotronic eGbR (vendor product page — consult for security advisories and fixed versions)
• MITRE ATT&CK — T1068, Exploitation for Privilege Escalation: https://attack.mitre.org/techniques/T1068/
• Microsoft — Recommended driver block rules / vulnerable driver blocklist guidance (for mitigating unmanaged kernel driver loading)
• CWE-367 — Time-of-check Time-of-use (TOCTOU) Race Condition: https://cwe.mitre.org/data/definitions/367.html

Threat actor and exploit-in-the-wild evidence: none identified. No public PoC, no exploit code, no Nuclei template, and no CISA KEV listing are associated with CVE-2026-79417 at the time of publication. EPSS has not scored this CVE.