Detect Communication Through Removable Media in Elastic Security
Adversaries can perform command and control between compromised hosts on potentially disconnected networks using removable media to transfer commands from system to system. Both systems would need to be compromised, with the likelihood that an Internet-connected system was compromised first and the second through lateral movement via Replication Through Removable Media. Commands and files are relayed from the disconnected system to the Internet-connected system to which the adversary has direct access. This technique has been observed in APT28/Fancy Bear operations using CHOPSTICK and USBStealer malware to bridge air-gapped networks, writing encoded command files to USB drives on internet-connected hosts and reading results from the same media when re-inserted.
MITRE ATT&CK
- Tactic
- Command and Control
- Canonical reference
- https://attack.mitre.org/techniques/T1092/
Elastic Detection Query
sequence by host.name with maxspan=2m
[any where event.category == "driver" and action == "installed" and dll.name : ("usbstor*", "USBSTOR*")]
[file where event.action in ("creation", "overwrite") and
file.path : ("D:\\*", "E:\\*", "F:\\*", "G:\\*", "H:\\*", "I:\\*") and
file.extension in~ ("exe", "dll", "bat", "cmd", "ps1", "vbs", "js", "hta", "dat", "bin", "enc", "tmp", "cfg", "db") and
not process.name in~ ("explorer.exe", "robocopy.exe", "xcopy.exe")]
OR
sequence by host.name with maxspan=2m
[any where event.category == "driver" and action == "installed" and dll.name : ("usbstor*")]
[file where event.action == "access" and
file.path : ("D:\\*", "E:\\*", "F:\\*", "G:\\*", "H:\\*")]
OR
process where event.type == "start" and
process.executable : ("D:\\*", "E:\\*", "F:\\*", "G:\\*", "H:\\*", "I:\\*") and
not process.name in~ ("setup.exe", "autorun.exe", "install.exe")Detects T1092 Communication Through Removable Media by identifying three behavioral patterns: (1) USB device insertion followed within 2 minutes by suspicious file creation on the drive, (2) USB mount followed by rapid file reads (command pickup pattern), and (3) process execution directly from removable drive letters. Covers both the C2 staging side (writing encoded data files) and the execution side (running payloads from USB).
Data Sources
Required Tables
False Positives & Tuning
- Legitimate software installations from USB drives by IT staff (e.g., deploying system images, BIOS updates via bootable USB)
- Backup agents (e.g., Acronis, Veeam) writing backup archives to external USB drives as part of scheduled jobs
- Portable application suites (PortableApps, U3) executing directly from USB — common in developer/sysadmin workflows
Other platforms for T1092
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 1Stage Encoded Command File on USB Drive
Expected signal: Sysmon Event ID 11 (FileCreate): TargetFilename=E:\system.dat, Image=powershell.exe. Sysmon Event ID 1 (Process Create): CommandLine containing 'Out-File' and 'E:\'. DeviceFileEvents in MDE: ActionType=FileCreated, FolderPath=E:\, FileName=system.dat, InitiatingProcessFileName=powershell.exe.
- Test 2Execute Payload from USB Drive
Expected signal: Sysmon Event ID 1 (Process Create): Image=cmd.exe, CommandLine=cmd.exe /c E:\update.bat. Parent process is cmd.exe or the test shell. Sysmon Event ID 11: TargetFilename=E:\update.bat and E:\output.dat. Security Event ID 4688 (if command line auditing enabled): NewProcessName contains E:\update.bat. DeviceProcessEvents: FileName=cmd.exe, ProcessCommandLine contains 'E:\update.bat'.
- Test 3Automated USB File Pickup Simulation
Expected signal: Multiple Sysmon Event ID 11 entries for file creation on E:\ by powershell.exe (cmd_*.dat and rsp_*.dat). Sysmon Event ID 1: PowerShell process with Get-Content and Out-File accessing removable drive. DeviceFileEvents: multiple FileCreated and FileRead actions on E:\ within a short time window — triggers the rapid-access-after-mount correlation branch.
- Test 4USB Device Serial Number Enumeration
Expected signal: Sysmon Event ID 1: powershell.exe with CommandLine containing 'USBSTOR' and 'Win32_DiskDrive'. Security Event ID 4663 (if object access auditing enabled on registry): access to HKLM\SYSTEM\CurrentControlSet\Enum\USBSTOR. DeviceProcessEvents: PowerShell process accessing registry via Get-ItemProperty with USBSTOR path.
References (9)
- https://attack.mitre.org/techniques/T1092/
- https://www.welivesecurity.com/2014/11/11/sednit-espionage-group-attacking-air-gapped-networks/
- https://www.fireeye.com/content/dam/fireeye-www/global/en/current-threats/pdfs/rpt-apt28.pdf
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-6416
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-devicefileevents-table
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceevents-table
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1092/T1092.md
- https://www.microsoft.com/en-us/security/blog/2016/01/14/sir-volume-19-is-now-available/
- https://docs.microsoft.com/en-us/sysinternals/downloads/sysmon
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