Detect Direct Volume Access in Splunk
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/
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
(
(Image="*\\vssadmin.exe" AND (CommandLine="*create shadow*" OR CommandLine="*list shadows*" OR CommandLine="*delete shadow*"))
OR (Image="*\\esentutl.exe" AND (CommandLine="*HarddiskVolumeShadowCopy*" OR CommandLine="*GLOBALROOT*" OR CommandLine="*/y *" OR CommandLine="*/vss*"))
OR (Image="*\\diskshadow.exe")
OR (Image="*\\ntdsutil.exe" AND (CommandLine="*ifm*" OR CommandLine="*activate instance*" OR CommandLine="*ntds*"))
OR (Image="*\\wbadmin.exe" AND (CommandLine="*start backup*" OR CommandLine="*start recovery*"))
OR ((Image="*\\powershell.exe" OR Image="*\\pwsh.exe") AND (CommandLine="*NinjaCopy*" OR CommandLine="*Invoke-NinjaCopy*" OR CommandLine="*PhysicalDrive*" OR CommandLine="*HarddiskVolumeShadowCopy*" OR CommandLine="*GLOBALROOT*"))
OR CommandLine="*\\\\.\\PhysicalDrive*"
OR CommandLine="*GLOBALROOT\\Device\\HarddiskVolumeShadowCopy*"
)
| eval ToolCategory=case(
match(Image, "vssadmin\.exe"), "ShadowCopyManagement",
match(Image, "esentutl\.exe"), "EsentutlVSS",
match(Image, "diskshadow\.exe"), "DiskShadow",
match(Image, "ntdsutil\.exe"), "NtdsutilIFM",
match(Image, "wbadmin\.exe"), "WindowsBackup",
(match(Image, "powershell\.exe") OR match(Image, "pwsh\.exe")), "PowerShellVolumeAccess",
true(), "DirectVolumeAccess"
)
| eval TargetsCredentials=if(
match(lower(CommandLine), "(ntds\.dit|ntds\.jfm|\bsam\b|\bsecurity\b|\bsystem\b|ntuser\.dat)"),
1, 0
)
| eval RiskScore=case(
TargetsCredentials=1, "Critical",
ToolCategory="PowerShellVolumeAccess", "High",
ToolCategory="EsentutlVSS", "High",
ToolCategory="NtdsutilIFM", "High",
true(), "Medium"
)
| eval CommandLine=CommandLine
| table _time, host, User, Image, CommandLine, ParentImage, ParentCommandLine,
ToolCategory, TargetsCredentials, RiskScore
| sort - _timeDetects direct volume access using Sysmon Event ID 1 (Process Creation). Covers vssadmin shadow copy operations, esentutl with VSS paths, diskshadow execution, ntdsutil IFM (Install From Media) mode used to dump NTDS, wbadmin backup operations, and PowerShell-based direct volume access tools including NinjaCopy. Evaluates command lines for credential file targets (ntds.dit, SAM, SYSTEM) to assign risk scores. Detects raw device path patterns (\\.\ PhysicalDrive, GLOBALROOT\Device\HarddiskVolumeShadowCopy) in any process context.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate backup software (Veeam, Acronis, Windows Server Backup) uses vssadmin and wbadmin for scheduled backup jobs — correlate with known backup windows and parent processes
- Database administrators running esentutl for NTDS or Exchange database maintenance and integrity checks — validate against change management records
- IT provisioning and domain replication tools (DFS-R, Active Directory replication) that interact with VSS for consistent snapshots
- Security scanning and DLP tools that enumerate shadow copies for data classification or compliance purposes
- Authorized penetration testers or red team operators performing credential extraction simulations — verify authorization documentation
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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