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

Analysis of asyncmac.sys: clean verdict, risk score 9/100. 0 YARA matches. SHA256 14985d6d2d52689c. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.

asyncmac.sys - Analysis Report

DriverShield analyzed the Windows kernel driver asyncmac.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	31232 bytes
Analyzed	2026-03-22
SHA256	14985d6d2d52689c1b012f64ed0d7c9c5f6badb51c4528bf6456d3eae2fe69a7
SHA1	2600a6522f9e13394be1fe0b0f329bfa28048250
MD5	d930aae80a55116d07c41e95de5671db

Driver identity

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

File description	MS Remote Access serial network driver
Product	Microsoft® Windows® Operating System
Company	Microsoft Corporation
Original filename	ASYNCMAC.SYS
Internal name	ASYNCMAC.SYS
File version	10.0.19041.1 (WinBuild.160101.0800)
Copyright	© Microsoft Corporation. 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	27 / 100
IOCTL dispatch surface	15 / 100
Known-vulnerable corpus	0 / 100
Code-signing state	50 / 100
Packing and entropy	0 / 100
Dynamic behaviour	0 / 100
CVE cross-reference	0 / 100

Kernel imports (10)

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

API	Risk	Why it matters
ObReferenceObjectByHandle	medium	Moderate risk - system modification capability
ObOpenObjectByPointer	medium	Moderate risk - system modification capability
KeInitializeEvent	low	Standard kernel API - generally benign
KeDelayExecutionThread	low	Standard kernel API - generally benign
ZwClose	low	Standard kernel API - generally benign
IofCompleteRequest	low	Standard kernel API - generally benign
KeSetEvent	low	Standard kernel API - generally benign
ExAllocatePoolWithTag	low	Standard kernel API - generally benign
KeWaitForSingleObject	low	Standard kernel API - generally benign
RtlInitUnicodeString	low	Standard kernel API - generally benign

IOCTL dispatch codes (5)

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
0x0080B08B	high	METHOD_NEITHER	FILE_DEVICE_CUSTOM Function #3106
0x002200F0	medium	METHOD_BUFFERED	FILE_DEVICE_UNKNOWN Function #60
0x00802B15	medium	METHOD_IN_DIRECT	FILE_DEVICE_CUSTOM Function #2757
0x002283E8	medium	METHOD_BUFFERED	FILE_DEVICE_UNKNOWN Function #250
0x003403B4	medium	METHOD_BUFFERED	FILE_DEVICE_DISK Function #237

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	0x4869	0x4A00	5.93	CODE, EXEC, READ
.rdata	0x09C8	0x0A00	5.41	IDATA, READ
.data	0x0290	0x0200	1.71	IDATA, READ, WRITE
.pdata	0x02C4	0x0400	3.02	IDATA, READ
.idata	0x0B06	0x0C00	4.4	IDATA, READ
INIT	0x0072	0x0200	1.68	CODE, EXEC, READ, DISCARD
GFIDS	0x0088	0x0200	1.16	IDATA, READ, DISCARD
.rsrc	0x0428	0x0600	2.5	IDATA, READ, DISCARD
.reloc	0x04F4	0x0600	4.86	IDATA, READ, DISCARD

Exploit mitigations

Control Flow Guard	Enabled
ASLR	Enabled
DEP	Enabled
Integrity check	Not enforced
Mitigation score	80 / 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.
Unsigned - The driver is not digitally signed. It requires test signing mode or a bootloader exploit to load on 64-bit Windows.

MITRE ATT&CK techniques (6)

Techniques this driver could enable if loaded by an adversary.

ID	Technique	Tactic
T1211	Exploitation for Defense Evasion	Defense Evasion
T1543.003	Windows Service	Persistence
T1553.002	Subvert Trust Controls: Code Signing	Defense Evasion
T1553.006	Code Signing Policy Modification	Defense Evasion
T1569.002	Service Execution	Execution
T1652	Device Driver Discovery	Discovery

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 asyncmac.sys

Is asyncmac.sys safe?

Based on DriverShield static and dynamic analysis, asyncmac.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 asyncmac.sys?

asyncmac.sys has a DriverShield composite risk score of 9/100, placing it in the clean verdict band. SHA256: 14985d6d2d52689c1b012f64ed0d7c9c5f6badb51c4528bf6456d3eae2fe69a7.

What is asyncmac.sys?

asyncmac.sys is a Windows kernel-mode driver (.sys) analyzed by DriverShield for vulnerabilities, BYOVD abuse potential, and malware indicators.