Detect Hidden Files and Directories in Microsoft Sentinel
Adversaries may set files and directories to be hidden to evade detection mechanisms. On Windows, the attrib command can set the hidden (+h) and system (+s) attributes on files and directories. On Linux/macOS, files and directories prefixed with a period (.) are hidden by convention. Adversaries use these techniques to hide malware, persistence mechanisms, and staging directories from casual file system inspection. Malware families including QakBot, APT28, RedCurl, and XCSSET use hidden file/directory techniques for persistence and evasion.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1564 Hide Artifacts
- Sub-technique
- T1564.001 Hidden Files and Directories
- Canonical reference
- https://attack.mitre.org/techniques/T1564/001/
KQL Detection Query
DeviceProcessEvents
| where Timestamp > ago(24h)
| where FileName =~ "attrib.exe"
| where ProcessCommandLine has "+h" or ProcessCommandLine has "+s" or ProcessCommandLine has "+r"
| extend HiddenAttr = ProcessCommandLine has "+h"
| extend SystemAttr = ProcessCommandLine has "+s"
| extend ReadOnly = ProcessCommandLine has "+r"
| extend SuspiciousTarget = ProcessCommandLine has_any ("Temp", "AppData", "ProgramData", "Recycle", "Windows")
| extend SuspiciousParent = InitiatingProcessFileName has_any ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe")
| project Timestamp, DeviceName, AccountName, ProcessCommandLine, InitiatingProcessFileName,
HiddenAttr, SystemAttr, ReadOnly, SuspiciousTarget, SuspiciousParent
| sort by Timestamp desc
union (
DeviceFileEvents
| where Timestamp > ago(24h)
| where ActionType == "FileAttributesModified"
| where AdditionalFields has "Hidden"
| project Timestamp, DeviceName, AccountName, FileName, FolderPath, InitiatingProcessFileName, AdditionalFields
| sort by Timestamp desc
)Detects hidden file/directory creation via attrib.exe on Windows, and file attribute modification events that set the Hidden attribute. Focuses on attrib.exe usage with +h/+s flags against user-writable directories and suspicious parent processes like scripting engines.
Data Sources
Required Tables
False Positives & Tuning
- System administrators using attrib.exe to hide configuration directories or sensitive files from user view
- Software installers that mark their data directories as hidden to prevent accidental user modification
- Windows system processes that legitimately set hidden/system attributes on operating system files and directories
- Backup software that marks shadow copy-related directories as hidden and system
Other platforms for T1564.001
Testing Methodology
Validate this detection against 3 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 1Hide File Using attrib.exe
Expected signal: Sysmon Event ID 1: attrib.exe with +h +s and Temp path. Security Event ID 4688. Sysmon Event ID 2 (File Time Changed) or file attribute modification event for the hidden file.
- Test 2Hide Directory Using attrib.exe from PowerShell
Expected signal: Sysmon Event ID 1: powershell.exe then attrib.exe with +h +s AppData path. SuspiciousParent and SuspiciousTarget both fire. Directory creation event (Sysmon EventCode=11) for the staging directory.
- Test 3Create Hidden File on Linux with Dot Prefix
Expected signal: Linux audit log: file creation event for /tmp/.hidden_payload.sh. Syslog: if auditd is configured with file watch on /tmp, the create and chmod events will appear. The file does not appear in 'ls /tmp' without -a flag.
References (4)
- https://attack.mitre.org/techniques/T1564/001/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1564.001/T1564.001.md
- https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/attrib
- https://www.elastic.co/blog/ten-process-injection-techniques-technical-survey-common-and-trending-process
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