stexstor.sys - Clean (9/100) - DriverShield Analysis

Analysis of stexstor.sys: clean verdict, risk score 9/100. 0 YARA matches. SHA256 766fd1e1d2f73de2. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.

stexstor.sys - Analysis Report

DriverShield analyzed the Windows kernel driver stexstor.sys and assigned a verdict of Clean with a composite risk score of 9/100, indicating no notable risk signals (0-29 band).

Verdict	Clean (9/100)
YARA matches	0
File size	31032 bytes
Code-signing signer	Microsoft Windows
Analyzed	2026-03-22
SHA256	766fd1e1d2f73de202fb337f6a6a5ba0317772aaaa644e9103bb5df438162f51
SHA1	535053509b1cdd9aa17fd50ed298ff2182d4be84
MD5	09dc471b4573f3d01d7e448b526ae70a

Driver identity

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

File description	Promise SuperTrak EX Series Driver for Windows x64
Product	Promise® SuperTrak EX Series
Company	Promise Technology, Inc.
Original filename	stexstor.sys
Internal name	stexstor.sys
File version	5.1.0000.10 (PART.121116-1330)
Copyright	© Promise Technology, Inc. All rights reserved.

How the 9/100 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	21 / 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 (2)

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

API	Risk	Why it matters
MmGetSystemRoutineAddress	high	Potentially dangerous - could be used for privilege escalation or security bypass
RtlInitUnicodeString	low	Standard kernel API - generally benign

IOCTL dispatch codes (7)

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
0x0034CB15	medium	METHOD_IN_DIRECT	FILE_DEVICE_DISK Function #709
0x0080968A	medium	METHOD_OUT_DIRECT	FILE_DEVICE_CUSTOM Function #1442
0xC350FE81	medium	METHOD_IN_DIRECT	CUSTOM_MSI Function #4000
0x00346424	medium	METHOD_BUFFERED	FILE_DEVICE_DISK Function #2313
0x003403C0	medium	METHOD_BUFFERED	FILE_DEVICE_DISK Function #240
0x00340036	medium	METHOD_OUT_DIRECT	FILE_DEVICE_DISK Function #13

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	0x3B9C	0x3C00	6.36	CODE, EXEC, READ
.rdata	0x04F4	0x0600	3.87	IDATA, READ
.data	0x0219	0x0200	2.08	IDATA, READ, WRITE
.pdata	0x024C	0x0400	2.65	IDATA, READ
INIT	0x0346	0x0400	4.09	CODE, EXEC, READ, WRITE, DISCARD
.rsrc	0x0420	0x0600	2.53	IDATA, READ, DISCARD
.reloc	0x007A	0x0200	0.6	IDATA, READ, DISCARD

Exploit mitigations

Control Flow Guard	Not enabled
ASLR	Enabled
DEP	Enabled
Integrity check	Not enforced
Mitigation score	55 / 100

No CFG - Control Flow Guard is not enabled. Indirect call targets are not validated, making the driver susceptible to control flow hijacking via corrupted function pointers or vtables.
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 stexstor.sys

Is stexstor.sys safe?

Based on DriverShield static and dynamic analysis, stexstor.sys is assessed as clean, with no notable risk signals. Its composite risk score is 9/100 (verdict: clean). Always validate findings independently before acting.

What is the risk score of stexstor.sys?

stexstor.sys has a DriverShield composite risk score of 9/100, placing it in the clean verdict band. SHA256: 766fd1e1d2f73de202fb337f6a6a5ba0317772aaaa644e9103bb5df438162f51.

What is stexstor.sys?

stexstor.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