Response playbooks, investigation guides, and Atomic Red Team tests are Pro-only. Upgrade to unlock the full detection package for THREAT-Exfil-USBRemovableMedia.
Upgrade to ProDetect Data Exfiltration via USB Removable Media in CrowdStrike LogScale
Adversaries and malicious insiders may copy sensitive files to a USB removable drive to exfiltrate data outside of network-monitored channels, bypassing DLP and network-based egress controls entirely. This is especially relevant in air-gapped or high-security environments where physical media is the only viable exfiltration path. Detection combines removable-storage device arrival events with high-volume file-copy activity from sensitive directories to the newly mounted volume within a short window.
MITRE ATT&CK
- Tactic
- Exfiltration
LogScale Detection Query
#repo="base_sensor"
#event_simpleName="FileWritten"
| TargetFileName = /(?i)^[D-G]:\\/
| bucket span=5m
| groupBy([ComputerName, UserName, _bucket], function=[count(as=FileCount)])
| where FileCount > 20
| sort(FileCount, order=desc, limit=1000)CrowdStrike LogScale CQL query bucketing FileWritten events targeting non-system drive letters into 5-minute windows per host and user, flagging bursts exceeding 20 writes as potential USB exfiltration staging (T1052.001).
Data Sources
Required Tables
False Positives & Tuning
- Authorized IT imaging or backup workflows writing many files to removable/external drives
- Drive letters reused for mapped network shares rather than physical USB media
Other platforms for THREAT-Exfil-USBRemovableMedia
Testing Methodology
Validate this detection against 2 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 1Bulk File Copy to Removable Drive via PowerShell
Expected signal: Sysmon Event ID 11: 30 FileCreate events with TargetFilename under E:\ within a few seconds. Windows Event ID 2003/2100 (or DeviceEvents UsbDriveMounted) showing the E: volume was previously connected. DeviceFileEvents recording each file write with FileSize and InitiatingProcessAccountName.
- Test 2Large Single-File Archive Copy to USB Drive
Expected signal: Sysmon Event ID 11: FileCreate for E:\archive_test.zip with FileSize ~60MB. DeviceFileEvents recording a single file write exceeding the 50MB threshold.
References (5)
- https://attack.mitre.org/techniques/T1052/001/
- https://learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/device-control-removable-storage-access-control
- https://learn.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-to-go-faq
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1052.001/T1052.001.md
- https://www.sans.org/white-papers/usb-exfiltration/
Unlock playbooks & atomic tests with Pro
Get the full detection package for THREAT-Exfil-USBRemovableMedia — response playbook and atomic red team tests, plus investigation guidance and hunting queries.
df00tech Pro — £29/user/month
Related Detections
Tactic Hub
Detection Variants (1)
Different telemetry and tradecraft for the same technique — pick the one that matches the data you collect.