Analysis of bs_rcio64.sys: vulnerable verdict, risk score 72/100. 3 YARA matches, 2/75 multi-engine detections. SHA256 d205286bffdf09bc. Kernel imports, IOCTL codes, MITRE ATT&CK, and code-signing details.
DriverShield analyzed the Windows kernel driver bs_rcio64.sys and assigned a verdict of Vulnerable with a composite risk score of 72/100, indicating a known or likely vulnerability surface (60-79 band).
| Verdict | Vulnerable (72/100) |
| YARA matches | 3 |
| Multi-engine detections | 2 / 75 |
| File size | 24592 bytes |
| Code-signing signer | Microsoft Windows Hardware Compatibility Publisher |
| Analyzed | 2026-09-06 |
| SHA256 | d205286bffdf09bc033c09e95c519c1c267b40c2ee8bab703c6a2d86741ccd3e |
| SHA1 | 5db61d00a001fd493591dc919f69b14713889fc5 |
| MD5 | b10b210c5944965d0dc85e70a0b19a42 |
Version resource data embedded in the bs_rcio64.sys PE header, as extracted by the analysis engine.
| File description | I/O Interface driver file |
|---|---|
| Product | BIOSTAR I/O driver |
| Company | BIOSTAR Group |
| Original filename | BS_RCIO64.sys |
| Internal name | I/O driver |
| File version | 10.0.1901.1100 |
| Copyright | Copyright (c) 2018-2019 BIOSTAR Group |
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 | 85 / 100 |
| Dangerous kernel imports | 100 / 100 |
| IOCTL dispatch surface | 33 / 100 |
| Known-vulnerable corpus | 100 / 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 bs_rcio64.sys, ranked by exploitation relevance.
| API | Risk | Why it matters |
|---|---|---|
| MmMapIoSpace | critical | Highly dangerous - potential for arbitrary code execution, memory corruption, or process termination |
| HalSetBusDataByOffset | high | Potentially dangerous - could be used for privilege escalation or security bypass |
| HalGetBusDataByOffset | high | Potentially dangerous - could be used for privilege escalation or security bypass |
| MmUnmapIoSpace | medium | Moderate risk - system modification capability |
| KeBugCheckEx | medium | Moderate risk - system modification capability |
| ObReferenceObjectByHandle | medium | Moderate risk - system modification capability |
| ZwClose | low | Standard kernel API - generally benign |
| RtlInitUnicodeString | low | Standard kernel API - generally benign |
| KeDelayExecutionThread | low | Standard kernel API - generally benign |
| IoCreateDevice | low | Standard kernel API - generally benign |
| IoDeleteDevice | low | Standard kernel API - generally benign |
| KeWaitForSingleObject | low | Standard kernel API - generally benign |
| IofCompleteRequest | low | Standard kernel API - generally benign |
| IoCreateSymbolicLink | low | Standard kernel API - generally benign |
| IoDeleteSymbolicLink | low | Standard kernel API - generally benign |
| KeSetEvent | 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 |
|---|---|---|---|
| 0x002200F0 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #60 |
| 0x0034870D | medium | METHOD_IN_DIRECT | FILE_DEVICE_DISK Function #451 |
| 0x0080249C | medium | METHOD_BUFFERED | FILE_DEVICE_CUSTOM Function #2343 |
| 0x00226114 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2117 |
| 0x002260C4 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2097 |
| 0x00226000 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2048 |
| 0x00226100 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2112 |
| 0x002261C4 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2161 |
| 0x00226118 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2118 |
| 0x002261C8 | medium | METHOD_BUFFERED | FILE_DEVICE_UNKNOWN Function #2162 |
| 0x003403AC | medium | METHOD_BUFFERED | FILE_DEVICE_DISK Function #235 |
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 | 0x23A8 | 0x2400 | 6.4 | CODE, EXEC, READ |
| .rdata | 0x02B0 | 0x0400 | 3.49 | IDATA, READ |
| .data | 0x014C | 0x0200 | 0.3 | IDATA, READ, WRITE |
| .pdata | 0x0168 | 0x0200 | 2.91 | IDATA, READ |
| INIT | 0x0550 | 0x0600 | 4.93 | CODE, EXEC, READ, WRITE, DISCARD |
| .rsrc | 0x0410 | 0x0600 | 2.43 | IDATA, READ, DISCARD |
| Control Flow Guard | Not enabled |
|---|---|
| ASLR | Not enabled |
| DEP | Not enabled |
| Integrity check | Not enforced |
| Mitigation score | 5 / 100 |
| Rule | Severity | Detects |
|---|---|---|
| PUA_VULN_Driver_Biostargroup_Iodriver_Biostariodriver_D205 | medium | Detects vulnerable driver mentioned in known-vulnerable driver corpus project using VersionInfo values from the PE header - BS_RCIO64.sys. Investigate matches in context: expected filenames or standar... |
| BYOVD_MemRW | critical | Phys memory mapping + device creation |
| SUSP_PhysMem | high | Physical memory mapping |
Techniques this driver could enable if loaded by an adversary.
| ID | Technique | Tactic |
|---|---|---|
| T1003 | OS Credential Dumping | Credential Access |
| T1003.001 | OS Credential Dumping: LSASS Memory | Credential Access |
| T1006 | Direct Volume Access | Defense Evasion |
| T1014 | Rootkit | Defense Evasion |
| T1055.012 | Process Hollowing | Defense Evasion |
| T1068 | Exploitation for Privilege Escalation | Privilege Escalation |
| T1542.001 | Pre-OS Boot: System Firmware | Persistence |
| T1543.003 | Windows Service | Persistence |
| T1562.001 | Impair Defenses | Defense Evasion |
| T1569.002 | Service Execution | Execution |
| T1601 | Modify System Image | Defense Evasion |
| T1652 | Device Driver Discovery | Discovery |
| Signer | Microsoft Windows Hardware Compatibility Publisher |
|---|---|
| Signer organisation | Microsoft Corporation |
| Issuer | Microsoft Windows Third Party Component CA 2014 |
| Serial | 33000000253A2738690A3451C1000000000025 |
| Valid from | 2018-09-06 21:30 UTC |
| Valid until | 2019-09-06 21:30 UTC (expired) |
| Signature validity | Not verified |
Engine angr, status completed, 21 paths explored at a maximum depth of 21. Vulnerability classes reached: 1. Exploitable paths: 0.
Corpus match: this hash is present in the known-vulnerable driver corpus DriverShield cross-references during analysis, which is why the score carries a full weighting on that component.
Based on DriverShield static and dynamic analysis, bs_rcio64.sys is flagged as vulnerable and is a potential Bring Your Own Vulnerable Driver (BYOVD) risk. Its composite risk score is 72/100 (verdict: vulnerable). Always validate findings independently before acting.
bs_rcio64.sys has a DriverShield composite risk score of 72/100, placing it in the vulnerable verdict band. SHA256: d205286bffdf09bc033c09e95c519c1c267b40c2ee8bab703c6a2d86741ccd3e.
bs_rcio64.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 Hardware Compatibility Publisher.
Related: Other drivers signed by Microsoft Windows Hardware Compatibility Publisher · What an IOCTL dispatch code is · How YARA matching feeds the score · BYOVD research index · full driver database · CVE library · code signing atlas