Analysis of kbldfltr.sys: suspicious verdict, risk score 58/100. 0 YARA matches. SHA256 e36e3f1d00dc139a. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.
DriverShield analyzed the Windows kernel driver kbldfltr.sys and assigned a verdict of Suspicious with a composite risk score of 58/100, indicating some risk signals warranting review (30-59 band).
| Verdict | Suspicious (58/100) |
| YARA matches | 0 |
| File size | 30088 bytes |
| Code-signing signer | Microsoft Windows |
| Analyzed | 2026-03-22 |
| SHA256 | e36e3f1d00dc139a70d906c89f3096de0433211cf652be338e84c16332a20a8c |
| SHA1 | 19fa95748320fe9c83c799c0f304ced2da18572a |
| MD5 | a7d9c5cad694ffb8711bf447534d7933 |
Version resource data embedded in the kbldfltr.sys PE header, as extracted by the analysis engine.
| File description | Keyboard Lockdown Subsystem |
|---|---|
| Product | Microsoft® Windows® Operating System |
| Company | Microsoft Corporation |
| Original filename | kbldfltr.sys |
| Internal name | kbldfltr.sys |
| File version | 10.0.19041.3636 (WinBuild.160101.0800) |
| Copyright | © Microsoft Corporation. All rights reserved. |
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 | 63 / 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-mode APIs resolved from the Import Address Table of kbldfltr.sys, ranked by exploitation relevance.
| API | Risk | Why it matters |
|---|---|---|
| DbgPrintEx | low | Standard kernel API - generally benign |
| ExAllocatePoolWithTag | low | Standard kernel API - generally benign |
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 |
|---|---|---|---|
| 0x00222000 | medium (known exploit) | METHOD_BUFFERED | Driver communication init |
| 0x0080832B | high | METHOD_NEITHER | FILE_DEVICE_CUSTOM Function #202 |
| 0x00223417 | high | METHOD_NEITHER | FILE_DEVICE_UNKNOWN Function #3333 |
| 0x002200F0 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #60 |
| 0x00808089 | medium | METHOD_IN_DIRECT | FILE_DEVICE_CUSTOM Function #34 |
| 0x003403A8 | medium | METHOD_BUFFERED | FILE_DEVICE_DISK Function #234 |
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 | 0x16E9 | 0x1800 | 6.1 | CODE, EXEC, READ |
| .rdata | 0x0E20 | 0x1000 | 4.8 | IDATA, READ |
| .data | 0x0380 | 0x0200 | 0.73 | IDATA, READ, WRITE |
| .pdata | 0x0174 | 0x0200 | 2.96 | IDATA, READ |
| .idata | 0x020A | 0x0400 | 2.2 | IDATA, READ |
| PAGE | 0x0834 | 0x0A00 | 5.3 | CODE, EXEC, READ |
| INIT | 0x053A | 0x0600 | 5.4 | CODE, EXEC, READ, DISCARD |
| GFIDS | 0x0024 | 0x0200 | 0.35 | IDATA, READ, DISCARD |
| .rsrc | 0x0410 | 0x0600 | 2.5 | IDATA, READ, DISCARD |
| .reloc | 0x01B4 | 0x0200 | 4.38 | IDATA, READ, DISCARD |
| Control Flow Guard | Enabled |
|---|---|
| ASLR | Enabled |
| DEP | Enabled |
| Integrity check | Not enforced |
| Mitigation score | 85 / 100 |
Techniques this driver could enable if loaded by an adversary.
| ID | Technique | Tactic |
|---|---|---|
| T1068 | Exploitation for Privilege Escalation | Privilege Escalation |
| 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 |
| T1569.002 | Service Execution | Execution |
| T1652 | Device Driver Discovery | Discovery |
| Signer | Microsoft Windows |
|---|---|
| Signer organisation | Microsoft Corporation |
| Issuer | Microsoft Windows Production PCA 2011 |
| Serial | 33000004158295A1A3D82E2857000000000415 |
| Valid from | 2023-02-03 00:05 UTC |
| Valid until | 2024-02-01 00:05 UTC (expired) |
| Signature validity | Not verified |
Engine angr, status static_approximation, 0 paths explored at a maximum depth of 0. Vulnerability classes reached: 0. Exploitable paths: 1.
Based on DriverShield static and dynamic analysis, kbldfltr.sys shows some suspicious signals and warrants manual review. Its composite risk score is 58/100 (verdict: suspicious). Always validate findings independently before acting.
kbldfltr.sys has a DriverShield composite risk score of 58/100, placing it in the suspicious verdict band. SHA256: e36e3f1d00dc139a70d906c89f3096de0433211cf652be338e84c16332a20a8c.
kbldfltr.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