Detect Exfiltration Over Other Network Medium in Splunk
Adversaries may attempt to exfiltrate data over a different network medium than the command and control channel. If the command and control network is a wired Internet connection, the exfiltration may occur over a WiFi connection, modem, cellular data connection, Bluetooth, or another radio frequency (RF) channel. Adversaries may choose to do this if they have sufficient access or proximity, and the connection might not be secured or defended as well as the primary Internet-connected channel because it is not routed through the same enterprise network monitoring infrastructure. This technique is commonly associated with insider threat scenarios and advanced adversaries who have achieved a foothold and seek to bypass perimeter DLP controls that monitor only the primary wired egress channel.
MITRE ATT&CK
- Tactic
- Exfiltration
- Canonical reference
- https://attack.mitre.org/techniques/T1011/
SPL Detection Query
index=wineventlog (sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1 OR sourcetype="WinEventLog:Security" EventCode=4688)
| eval Image=coalesce(Image, NewProcessName)
| eval CommandLine=coalesce(CommandLine, ProcessCommandLine)
| eval ParentImage=coalesce(ParentImage, ParentProcessName)
| eval Image_lc=lower(Image)
| eval CmdLine_lc=lower(CommandLine)
| eval IsNetshWlan=if(match(Image_lc, "netsh\.exe") AND (match(CmdLine_lc, "wlan") OR match(CmdLine_lc, "hostednetwork") OR match(CmdLine_lc, "mobile\s*hotspot")), 1, 0)
| eval IsBluetoothTool=if(match(Image_lc, "(fsquirt\.exe|bttray\.exe)"), 1, 0)
| eval IsPSWirelessManip=if(match(Image_lc, "(powershell\.exe|pwsh\.exe)") AND match(CmdLine_lc, "(bluetooth|wlan|wifi|netadapter|get-netadapter|new-wifiprofile|mobilebroadband|set-netconnectionprofile|softap|hostednetwork)"), 1, 0)
| eval IsHotspotCreation=if(match(CmdLine_lc, "(hostednetwork|start\s+hostednetwork|mode=allow|softap)"), 1, 0)
| eval SuspicionScore=IsNetshWlan + IsBluetoothTool + IsPSWirelessManip + IsHotspotCreation
| where SuspicionScore > 0
| table _time, host, User, Image, CommandLine, ParentImage, ParentCommandLine, IsNetshWlan, IsBluetoothTool, IsPSWirelessManip, IsHotspotCreation, SuspicionScore
| sort - _timeDetects exfiltration over alternative network mediums using Sysmon Event ID 1 or Security Event ID 4688 (Process Creation). Evaluates process names and command lines for wireless configuration utilities (netsh wlan), Bluetooth file transfer tools (fsquirt.exe, bttray.exe), and PowerShell wireless adapter manipulation. Assigns a cumulative suspicion score across four indicator categories; events scoring 2 or higher should be prioritized for immediate triage. Hotspot creation (IsHotspotCreation=1) combined with any other indicator is a high-confidence exfiltration staging signal.
Data Sources
Required Sourcetypes
False Positives & Tuning
- IT administrators running netsh wlan commands to diagnose wireless connectivity issues or manage corporate wireless profiles
- Help desk staff using netsh wlan show commands for network troubleshooting on user endpoints
- MDM/EMM agents (Microsoft Intune, SCCM/MECM) deploying or updating wireless configuration profiles via PowerShell
- End users legitimately transferring personal files to Bluetooth peripherals (headphones, phones) via fsquirt.exe
- Network assessment or inventory tools querying wireless adapter status and available SSIDs
Other platforms for T1011
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 1Create and Start WiFi Hosted Network via netsh
Expected signal: Sysmon Event ID 1: Two Process Create events — first with CommandLine containing 'wlan set hostednetwork mode=allow ssid=df00tech-test-exfil', second containing 'wlan start hostednetwork'. Security Event ID 4688 if command-line auditing is enabled. Windows WLAN-AutoConfig Operational Event ID 11000 (Microsoft-Windows-WLAN-AutoConfig: The wireless Hosted Network started successfully). Registry change under HKLM\SYSTEM\CurrentControlSet\Services\WlanSvc\Parameters\HostedNetworkSettings.
- Test 2Launch Bluetooth File Transfer Wizard (fsquirt.exe)
Expected signal: Sysmon Event ID 1: Process Create with Image=C:\Windows\System32\fsquirt.exe, ParentImage=powershell.exe, User=current user. Security Event ID 4688 if command-line auditing is enabled. Bluetooth-Driver Operational log may record adapter activation. No file creation or network connection events since no transfer is completed.
- Test 3Wireless Adapter Reconnaissance via PowerShell and netsh
Expected signal: Sysmon Event ID 1: Process Create for powershell.exe with CommandLine containing 'Get-NetAdapter' and 'PhysicalMediaType'. Child Sysmon Event ID 1 processes for netsh.exe with CommandLine 'wlan show interfaces' and 'wlan show profiles'. PowerShell ScriptBlock Log Event ID 4104 with the full script content.
- Test 4Linux Bluetooth Device Discovery and OBEX Transfer Preparation
Expected signal: Linux auditd (if configured with execve rules): SYSCALL records type=EXECVE for hciconfig, hcitool, bluetoothctl, and rfkill with their arguments and auid/uid/pid context. Syslog/journal entries from the Bluetooth daemon (bluetoothd) showing adapter state transitions. If Microsoft Defender for Linux is deployed, DeviceProcessEvents will record these process creation events.
References (8)
- https://attack.mitre.org/techniques/T1011/
- https://attack.mitre.org/techniques/T1011/001/
- https://learn.microsoft.com/en-us/windows-server/networking/technologies/netsh/netsh-contexts
- https://learn.microsoft.com/en-us/windows/win32/wlanapi/about-the-wireless-hosted-network
- https://learn.microsoft.com/en-us/windows-hardware/drivers/bluetooth/bluetooth-faq--transferring-files-faq
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1011/T1011.md
- https://github.com/SigmaHQ/sigma/tree/master/rules/windows/network_connection
- https://learn.microsoft.com/en-us/windows/win32/bluetooth/bluetooth-and-bluetooth-le
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