Analysis of bttflt.sys: suspicious verdict, risk score 30/100. 1 YARA match. SHA256 8de3b7c87d88cf37. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.
DriverShield analyzed the Windows kernel driver bttflt.sys and assigned a verdict of Suspicious with a composite risk score of 30/100, indicating some risk signals warranting review (30-59 band).
| Verdict | Suspicious (30/100) |
| YARA matches | 1 |
| File size | 43832 bytes |
| Code-signing signer | Microsoft Windows |
| Analyzed | 2026-03-22 |
| SHA256 | 8de3b7c87d88cf375417355a7c5052b2de38805b563d61d0e483db4ad96bd741 |
| SHA1 | 19187f28846ad507f06baf416ce4cc5a4cc70cd7 |
| MD5 | 4ff20e869fe2b5a0b8ce2e8be61c7f7f |
Version resource data embedded in the bttflt.sys PE header, as extracted by the analysis engine.
| File description | VHD BTT Filter Driver |
|---|---|
| Product | Microsoft® Windows® Operating System |
| Company | Microsoft Corporation |
| Original filename | bttflt.sys |
| Internal name | bttflt.sys |
| File version | 10.0.19041.1 (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 | 30 / 100 |
| Dangerous kernel imports | 100 / 100 |
| IOCTL dispatch surface | 33 / 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 bttflt.sys, ranked by exploitation relevance.
| API | Risk | Why it matters |
|---|---|---|
| MmGetPhysicalAddress | high | Potentially dangerous - could be used for privilege escalation or security bypass |
| MmGetSystemRoutineAddress | high | Potentially dangerous - could be used for privilege escalation or security bypass |
| MmUnmapIoSpace | medium | Moderate risk - system modification capability |
| KeInitializeEvent | low | Standard kernel API - generally benign |
| IoBuildDeviceIoControlRequest | low | Standard kernel API - generally benign |
| ExAllocatePoolWithTag | low | Standard kernel API - generally benign |
| KeWaitForSingleObject | low | Standard kernel API - generally benign |
| IoCreateDevice | low | Standard kernel API - generally benign |
| IoDeleteDevice | low | Standard kernel API - generally benign |
| RtlInitUnicodeString | low | Standard kernel API - generally benign |
| IofCompleteRequest | 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 |
|---|---|---|---|
| 0x0080878B | high | METHOD_NEITHER | FILE_DEVICE_CUSTOM Function #482 |
| 0x002200F0 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #60 |
| 0x002203E8 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #250 |
| 0x0080EC81 | medium | METHOD_IN_DIRECT | FILE_DEVICE_CUSTOM Function #2848 |
| 0x0080249C | medium | METHOD_BUFFERED | FILE_DEVICE_CUSTOM Function #2343 |
| 0x00802484 | medium | METHOD_BUFFERED | FILE_DEVICE_CUSTOM Function #2337 |
| 0x008024AC | medium | METHOD_BUFFERED | FILE_DEVICE_CUSTOM Function #2347 |
| 0x00808311 | medium | METHOD_IN_DIRECT | FILE_DEVICE_CUSTOM Function #196 |
| 0x0022B941 | medium | METHOD_IN_DIRECT | FILE_DEVICE_UNKNOWN Function #3664 |
| 0x00802494 | medium | METHOD_BUFFERED | FILE_DEVICE_CUSTOM Function #2341 |
| 0x00340388 | medium | METHOD_BUFFERED | FILE_DEVICE_DISK Function #226 |
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 | 0x38A9 | 0x3A00 | 6.13 | CODE, EXEC, READ |
| .rdata | 0x10D8 | 0x1200 | 5.15 | IDATA, READ |
| .data | 0x0260 | 0x0200 | 0.34 | IDATA, READ, WRITE |
| .pdata | 0x048C | 0x0600 | 3.43 | IDATA, READ |
| .idata | 0x0676 | 0x0800 | 3.96 | IDATA, READ |
| PAGE | 0x1BC6 | 0x1C00 | 6.22 | CODE, EXEC, READ |
| INIT | 0x0252 | 0x0400 | 3.91 | CODE, EXEC, READ, DISCARD |
| GFIDS | 0x0078 | 0x0200 | 1.08 | IDATA, READ, DISCARD |
| .rsrc | 0x03F8 | 0x0400 | 3.3 | IDATA, READ, DISCARD |
| .reloc | 0x0304 | 0x0400 | 4.27 | IDATA, READ, DISCARD |
| Control Flow Guard | Enabled |
|---|---|
| ASLR | Enabled |
| DEP | Enabled |
| Integrity check | Not enforced |
| Mitigation score | 85 / 100 |
| Rule | Severity | Detects |
|---|---|---|
| SUSP_PhysMem | high | Physical memory mapping |
Techniques this driver could enable if loaded by an adversary.
| ID | Technique | Tactic |
|---|---|---|
| T1003.001 | OS Credential Dumping: LSASS Memory | Credential Access |
| T1055.012 | Process Hollowing | Defense Evasion |
| 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 | System Services: Service Execution | Execution |
| T1652 | Device Driver Discovery | Discovery |
| 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 |
Engine angr, status no_findings, 0 paths explored at a maximum depth of 0. Vulnerability classes reached: 0. Exploitable paths: 0.
Based on DriverShield static and dynamic analysis, bttflt.sys shows some suspicious signals and warrants manual review. Its composite risk score is 30/100 (verdict: suspicious). Always validate findings independently before acting.
bttflt.sys has a DriverShield composite risk score of 30/100, placing it in the suspicious verdict band. SHA256: 8de3b7c87d88cf375417355a7c5052b2de38805b563d61d0e483db4ad96bd741.
bttflt.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 · How YARA matching feeds the score · BYOVD research index · full driver database · CVE library · code signing atlas