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Upgrade to ProDetect Data Exfiltration via USB Removable Media in Sumo Logic CSE
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
Sumo Detection Query
(_sourceCategory="windows/sysmon" OR _sourceCategory="siem/windows/sysmon")
| parse "EventID>*<" as EventID nodrop
| parse "TargetFilename>*<" as TargetFilename nodrop
| parse "User>*<" as User nodrop
| parse "Computer>*<" as Computer nodrop
| where EventID = "11"
| where TargetFilename matches "D:\\*" OR TargetFilename matches "E:\\*" OR TargetFilename matches "F:\\*" OR TargetFilename matches "G:\\*"
| timeslice 5m
| count as FileCount by Computer, User, _timeslice
| where FileCount > 20
| sort by FileCount descSumo Logic query aggregating Sysmon Event ID 11 (FileCreate) records targeting non-system drive letters into 5-minute windows, flagging bursts exceeding 20 file writes per host/user as potential USB exfiltration staging.
Data Sources
Required Tables
False Positives & Tuning
- Authorized backup or imaging jobs writing many files to external drives in a short window
- Users with mapped network drives assigned letters in the D:-G: range
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/
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Related Detections
Tactic Hub
Detection Variants (1)
Different telemetry and tradecraft for the same technique — pick the one that matches the data you collect.