ntosext.sys - Clean (8/100) - DriverShield Analysis

Analysis of ntosext.sys: clean verdict, risk score 8/100. 0 YARA matches. SHA256 892ef5335574edc7. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.

ntosext.sys - Analysis Report

DriverShield analyzed the Windows kernel driver ntosext.sys and assigned a verdict of Clean with a composite risk score of 8/100, indicating no notable risk signals (0-29 band).

Verdict	Clean (8/100)
YARA matches	0
File size	20792 bytes
Code-signing signer	Microsoft Windows
Analyzed	2026-03-22
SHA256	892ef5335574edc7367745b31ad482067e26403edbd1011fc02c0577997e6a8a
SHA1	b7cf4b067999bb3e3c60b3b3c625bbad3f3c50d8
MD5	ee214959e3612b1758c36b4a074dc3f1

Driver identity

Version resource data embedded in the ntosext.sys PE header, as extracted by the analysis engine.

File description	NTOS extension host driver
Product	Microsoft® Windows® Operating System
Company	Microsoft Corporation
Original filename	ntosext.sys
Internal name	ntosext.sys
File version	10.0.19041.1 (WinBuild.160101.0800)
Copyright	© Microsoft Corporation. All rights reserved.

How the 8/100 score breaks down

Each component is scored 0-100 and then weighted into the composite. See the analysis methodology for the exact formula.

Component	Sub-score
Multi-engine consensus	0 / 100
YARA signature matches	0 / 100
Dangerous kernel imports	15 / 100
IOCTL dispatch surface	9 / 100
Known-vulnerable corpus	0 / 100
Code-signing state	80 / 100
Packing and entropy	0 / 100
Dynamic behaviour	0 / 100
CVE cross-reference	0 / 100

Kernel imports (7)

Kernel-mode APIs resolved from the Import Address Table of ntosext.sys, ranked by exploitation relevance.

API	Risk	Why it matters
ExAllocatePoolWithTag	low	Standard kernel API - generally benign
RtlInitUnicodeString	low	Standard kernel API - generally benign
RtlInitAnsiString	low	Standard kernel API - generally benign
KeInitializeEvent	low	Standard kernel API - generally benign
SeSinglePrivilegeCheck	low	Standard kernel API - generally benign
KeWaitForSingleObject	low	Standard kernel API - generally benign
KeSetEvent	low	Standard kernel API - generally benign

IOCTL dispatch codes (3)

Control codes reachable through the driver dispatch routine. Codes tied to published exploit code are flagged, since they are the primary Bring Your Own Vulnerable Driver (BYOVD) entry points.

Code	Severity	Transfer	Description
0x002200F0	medium	METHOD_BUFFERED	FILE_DEVICE_UNKNOWN Function #60
0x00802000	medium	METHOD_BUFFERED	FILE_DEVICE_CUSTOM Function #2048
0x00340394	medium	METHOD_BUFFERED	FILE_DEVICE_DISK Function #229

PE sections

Section layout and Shannon entropy. High entropy in a code section is a packing or encryption indicator.

Section	Virtual size	Raw size	Entropy	Flags
.text	0x0229	0x0400	3.51	CODE, EXEC, READ
.rdata	0x04B0	0x0600	3.13	IDATA, READ
.data	0x0110	0x0200	0.28	IDATA, READ, WRITE
.pdata	0x0108	0x0200	2.07	IDATA, READ
.idata	0x0552	0x0600	4.07	IDATA, READ
PAGE	0x074B	0x0800	5.48	CODE, EXEC, READ
.edata	0x00BB	0x0200	2.12	IDATA, READ
INIT	0x0282	0x0400	4.21	CODE, EXEC, READ, DISCARD
GFIDS	0x0038	0x0200	0.47	IDATA, READ, DISCARD
.rsrc	0x0408	0x0600	2.43	IDATA, READ, DISCARD
.reloc	0x0130	0x0200	2.87	IDATA, READ, DISCARD

Exploit mitigations

Control Flow Guard	Enabled
ASLR	Enabled
DEP	Enabled
Integrity check	Not enforced
Mitigation score	85 / 100

CFG Enabled - Control Flow Guard is active - indirect calls are validated against a bitmap of valid targets at runtime.
ASLR Enabled - Address Space Layout Randomization is active - base address is randomized on each load.
DEP/NX Enabled - Data Execution Prevention is active - non-executable pages cannot be executed.
Expired Certificate - The driver is signed but the certificate has expired. Windows may still load it depending on revocation policy.

MITRE ATT&CK techniques (5)

Techniques this driver could enable if loaded by an adversary.

ID	Technique	Tactic
T1071	Application Layer Protocol	Command and Control
T1211	Exploitation for Defense Evasion	Defense Evasion
T1543.003	Windows Service	Persistence
T1553.002	Subvert Trust Controls: Code Signing	Defense Evasion
T1652	Device Driver Discovery	Discovery

Code-signing chain

Signer	Microsoft Windows
Signer organisation	Microsoft Corporation
Issuer	Microsoft Windows Production PCA 2011
Serial	330000023241FB59996DCC4DFF000000000232
Valid from	2019-05-02 21:24 UTC
Valid until	2020-05-02 21:24 UTC (expired)
Signature validity	Not verified

Certificate revision: 0x0200
Certificate type: PKCS#7
Chain: Microsoft Windows Production PCA 2011

Symbolic execution

Engine angr, status no_findings, 0 paths explored at a maximum depth of 0. Vulnerability classes reached: 0. Exploitable paths: 0.

Frequently asked questions about ntosext.sys

Is ntosext.sys safe?

Based on DriverShield static and dynamic analysis, ntosext.sys is assessed as clean, with no notable risk signals. Its composite risk score is 8/100 (verdict: clean). Always validate findings independently before acting.

What is the risk score of ntosext.sys?

ntosext.sys has a DriverShield composite risk score of 8/100, placing it in the clean verdict band. SHA256: 892ef5335574edc7367745b31ad482067e26403edbd1011fc02c0577997e6a8a.

What is ntosext.sys?

ntosext.sys is a Windows kernel-mode driver (.sys) analyzed by DriverShield for vulnerabilities, BYOVD abuse potential, and malware indicators. It is code-signed by Microsoft Windows.

Related: Other drivers signed by Microsoft Windows · What an IOCTL dispatch code is · BYOVD research index · full driver database · CVE library · code signing atlas