Detect Exfiltration Over Other Network Medium in Google Chronicle
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/
YARA-L Detection Query
rule t1011_exfil_other_network_medium {
meta:
author = "Detection Engineering"
description = "Detects T1011 - Exfiltration Over Other Network Medium via wireless hotspot creation, Bluetooth file transfer utilities, or PowerShell wireless adapter manipulation from suspicious parent processes"
mitre_attack_tactic = "Exfiltration"
mitre_attack_technique = "T1011"
severity = "HIGH"
priority = "HIGH"
false_positives = "IT admin netsh diagnostics, legitimate Bluetooth transfers, MDM or endpoint tooling using wireless PowerShell cmdlets"
version = "1.0"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
(
(
re.regex($e.target.process.file.full_path, `(?i)netsh\.exe$`) and
(
re.regex($e.target.process.command_line, `(?i)wlan`) or
re.regex($e.target.process.command_line, `(?i)hostednetwork`) or
re.regex($e.target.process.command_line, `(?i)mode=(allow|disallow)`) or
re.regex($e.target.process.command_line, `(?i)mobile.hotspot`)
)
) or
re.regex($e.target.process.file.full_path, `(?i)(fsquirt|bttray)\.exe$`) or
(
re.regex($e.target.process.file.full_path, `(?i)(powershell|pwsh)\.exe$`) and
re.regex($e.target.process.command_line, `(?i)(bluetooth|wlan|wifi|netadapter|get-netadapter|new-wifiprofile|hostednetwork|softap|mobilebroadband|set-netconnectionprofile)`) and
(
re.regex($e.principal.process.file.full_path, `(?i)(cmd|powershell|wscript|cscript|mshta|rundll32|regsvr32|schtasks)\.exe$`) or
re.regex($e.target.process.command_line, `(?i)(-enc|-EncodedCommand|Compress-Archive|DownloadFile|exfil)`)
)
)
)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting T1011 exfiltration over alternate network mediums using UDM PROCESS_LAUNCH events. Matches target.process.file.full_path and target.process.command_line against three detection branches: netsh wlan hotspot and adapter commands, Bluetooth file transfer utilities (fsquirt.exe, bttray.exe), and PowerShell wireless adapter manipulation initiated from suspicious parent processes (principal.process) or with obfuscation and exfil indicators in the command line. All regex patterns use (?i) case-insensitive flag.
Data Sources
Required Tables
False Positives & Tuning
- IT administrators executing netsh wlan set or show commands during wireless infrastructure provisioning, troubleshooting runbooks, or post-imaging network validation scripts
- Bluetooth peripheral onboarding workflows that invoke fsquirt.exe or bttray.exe as part of standard OS-level driver installation or device pairing initiated by IT or end users
- Enterprise endpoint management suites such as SCCM, Intune, or Tanium invoking PowerShell to query Get-NetAdapter or Set-NetConnectionProfile state during scheduled compliance checks or hardware discovery cycles
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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