Detect Direct Volume Access in Google Chronicle
Adversaries may directly access a volume to bypass file access controls and file system monitoring. Windows allows programs to have direct access to logical volumes, enabling reads and writes directly from the drive by analyzing file system data structures. This technique bypasses Windows file access controls and file system monitoring tools. Utilities such as NinjaCopy (PowerShell), vssadmin, wbadmin, and esentutl can be used to create shadow copies or access locked files (such as ntds.dit, SYSTEM hive, and SAM) directly from disk. Real-world actors including Scattered Spider and Volt Typhoon have leveraged Volume Shadow Copy Service (VSS) to extract credential stores without triggering standard file access controls.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1006 Direct Volume Access
- Canonical reference
- https://attack.mitre.org/techniques/T1006/
YARA-L Detection Query
rule T1006_Direct_Volume_Access {
meta:
author = "Detection Engineering"
description = "Detects T1006 Direct Volume Access - VSS shadow copy manipulation tools, direct physical volume path access, and PowerShell-based raw disk API usage targeting credential stores (ntds.dit, SAM, SECURITY)"
mitre_attack_tactic = "Credential Access"
mitre_attack_technique = "T1006"
severity = "HIGH"
confidence = "HIGH"
platform = "Windows"
created = "2024-01-01"
version = "1.0"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
(
(
re.regex($e.target.process.file.full_path,
`(?i)(vssadmin|esentutl|diskshadow|ntdsutil|wbadmin)\.exe$`) and
re.regex($e.target.process.command_line,
`(?i)(create shadow|list shadow|delete shadow|HarddiskVolumeShadowCopy|GLOBALROOT|\/y |\/vss|ifm|activate instance|set context|add volume|start backup|start recovery)`)
) or
(
re.regex($e.target.process.file.full_path, `(?i)(powershell|pwsh)\.exe$`) and
re.regex($e.target.process.command_line,
`(?i)(NinjaCopy|Invoke-NinjaCopy|PhysicalDrive|HarddiskVolumeShadowCopy|GLOBALROOT|GetDriveGeometry|FSCTL_GET_NTFS_VOLUME_DATA|DeviceIoControl)`)
) or
(
re.regex($e.target.process.command_line,
`(?i)(PhysicalDrive|HarddiskVolumeShadowCopy|HarddiskVolume[0-9]|GLOBALROOT)`) and
not re.regex($e.target.process.file.full_path, `(?i)(vssvc|svchost|wmiprvse)\.exe$`)
)
)
condition:
$e
}Chronicle YARA-L 2.0 detection rule for T1006 Direct Volume Access operating on UDM PROCESS_LAUNCH events. Three detection branches: (1) known VSS/volume management tools (vssadmin, esentutl, diskshadow, ntdsutil, wbadmin) with suspicious arguments indicating shadow copy manipulation or credential access; (2) PowerShell processes invoking raw disk APIs or NinjaCopy tool variants; (3) any non-system process with direct volume path strings in the command line. Uses re.regex with backtick raw strings for clean pattern matching without double-escaping.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise backup infrastructure systems (Veeam backup servers, Azure Backup MARs agent, Windows Server Backup scheduled tasks) that legitimately invoke vssadmin.exe and wbadmin.exe — create reference list exclusions for known backup service account UPNs and backup server hostnames in Chronicle
- Active Directory engineers creating IFM installation media for new domain controller deployments using ntdsutil.exe — this produces an exact pattern match on 'activate instance ntds' and 'ifm' that is operationally indistinguishable at the command-line level; correlate against approved change requests
- EDR and security tooling (Carbon Black, SentinelOne, CrowdStrike Falcon) that periodically access raw volume data or shadow copy paths as part of behavioral monitoring, forensic snapshot collection, or integrity baseline operations
Other platforms for T1006
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1VSS Shadow Copy Creation and NTDS Extraction via esentutl
Expected signal: Sysmon Event ID 1: Process Create for vssadmin.exe with CommandLine containing 'create shadow /for=C:'. Second Sysmon Event ID 1: esentutl.exe with CommandLine containing the \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy path and '/vss'. Security Event ID 4688 for both processes if command line auditing is enabled. Microsoft-Windows-StorageService/Operational events for VSS snapshot creation. Sysmon Event ID 11 (File Create) for SYSTEM.bak in %TEMP%.
- Test 2Diskshadow Script-Based Shadow Copy and File Exposure
Expected signal: Sysmon Event ID 1: diskshadow.exe with CommandLine containing '/s' and the .dsh script path. Sysmon Event ID 11: creation of dsh_test.dsh in %TEMP% by powershell.exe. Security Event ID 4688 for diskshadow.exe. Microsoft-Windows-StorageService/Operational events for VSS snapshot creation via diskshadow. If drive Z: is exposed, subsequent file access on Z: generates normal file system events attributed to the accessing process.
- Test 3ntdsutil IFM Media Creation for NTDS Extraction
Expected signal: Sysmon Event ID 1: ntdsutil.exe with CommandLine containing 'ifm', 'create full', and the output path. Security Event ID 4688 for ntdsutil.exe. On a domain controller: Security Event ID 4656/4663 for NTDS directory handle access, and Sysmon Event ID 11 for file creation of ntds.dit and SYSTEM in the IFM output directory. On a non-DC: ntdsutil exits with an error (0x80070003 - path not found for NTDS) but process creation event still fires.
- Test 4PowerShell Direct Physical Drive Read Simulation
Expected signal: Sysmon Event ID 1: powershell.exe with CommandLine containing '\\.\PhysicalDrive0' and 'FileOpen'. Security Event ID 4688 if command line auditing is enabled. If Object Access auditing covers raw disk handles: Security Event ID 4656 for handle request to PhysicalDrive0. This command will fail with 'Access Denied' for non-elevated users, but the process creation event still fires and matches the detection pattern.
References (10)
- https://attack.mitre.org/techniques/T1006/
- https://github.com/PowerShellMafia/PowerSploit/blob/master/Exfiltration/Invoke-NinjaCopy.ps1
- https://lolbas-project.github.io/lolbas/Binaries/Esentutl/
- https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/vssadmin
- https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/diskshadow
- https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/cc753455(v=ws.11)
- https://www.microsoft.com/en-us/security/blog/2023/10/25/octo-tempest-crosses-boundaries-to-facilitate-extortion-encryption-and-destruction/
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-038a
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1006/T1006.md
- http://www.codeproject.com/Articles/32169/FDump-Dumping-File-Sectors-Directly-from-Disk-usin
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