Detect Exfiltration Over Bluetooth in Google Chronicle
Adversaries may attempt to exfiltrate data over Bluetooth rather than the command and control channel. If the command and control network is a wired Internet connection, an adversary may opt to exfiltrate data using a Bluetooth communication channel. Adversaries may choose to do this if they have sufficient access and proximity. Bluetooth connections might not be secured or defended as well as the primary Internet-connected channel because it is not routed through the same enterprise network. Real-world examples include the Flame malware's BeetleJuice module, which transmitted encoded data over Bluetooth and acted as a Bluetooth beacon to identify nearby Bluetooth-enabled devices.
MITRE ATT&CK
- Tactic
- Exfiltration
- Sub-technique
- T1011.001 Exfiltration Over Bluetooth
- Canonical reference
- https://attack.mitre.org/techniques/T1011/001/
YARA-L Detection Query
rule t1011_001_exfiltration_over_bluetooth {
meta:
author = "Detection Engineering"
description = "Detects potential data exfiltration over Bluetooth (T1011.001) via Bluetooth tool execution, Bluetooth stack registry modification, or Bluetooth-related file creation activity."
mitre_attack_tactic = "Exfiltration"
mitre_attack_technique = "T1011.001"
mitre_attack_url = "https://attack.mitre.org/techniques/T1011/001/"
severity = "HIGH"
priority = "HIGH"
platforms = "Windows, Linux"
created = "2024-01-01"
events:
(
$e.metadata.event_type = "PROCESS_LAUNCH" and
(
re.regex($e.target.process.file.full_path,
`(?i)(btattach|btmgmt|hciconfig|hcitool|hcidump|bluetoothctl|sdptool|rfcomm|obexftp|obexd|bluetooth-sendto|fsquirt\.exe)`) or
re.regex($e.target.process.command_line,
`(?i)(bluetooth|rfcomm|obex|hcitool|hciconfig|btmgmt|bluetoothctl|bt-adapter|bluetoothd)`)
)
) or
(
$e.metadata.event_type = "REGISTRY_MODIFICATION" and
re.regex($e.target.registry.registry_key,
`(?i)(bluetooth|bthport|bthenum|bthle|rfcomm|obex)`)
) or
(
$e.metadata.event_type = "FILE_CREATION" and
re.regex($e.target.file.full_path,
`(?i)(bluetooth|rfcomm|obex|btooth)`)
)
condition:
$e
}Chronicle YARA-L 2.0 detection rule for T1011.001 Bluetooth exfiltration using UDM normalized event fields. The rule triggers on any of three UDM event types: PROCESS_LAUNCH events where the target process path or command line matches known Bluetooth management utilities; REGISTRY_MODIFICATION events where the target registry key path contains Bluetooth stack component identifiers (BTHPORT, BTHENUM, BthLE, RFCOMM, OBEX); or FILE_CREATION events where the target file path contains Bluetooth-related strings. All matching uses case-insensitive regex via re.regex() against normalized UDM fields.
Data Sources
Required Tables
False Positives & Tuning
- IT management scripts invoking btmgmt, hciconfig, or bluetoothctl to pair enterprise Bluetooth peripherals during scheduled device provisioning or refresh cycles, generating PROCESS_LAUNCH matches.
- Windows Plug-and-Play subsystem or Bluetooth driver installers writing to BTHPORT, BTHENUM, or BthLE registry paths during authorized hardware onboarding, generating REGISTRY_MODIFICATION matches.
- Authorized IoT developers on tracked workstations executing obexftp, rfcomm, or sdptool for Bluetooth stack testing as part of product development workflows covered under a threat exception policy.
- Linux hosts that load Bluetooth kernel modules and invoke hciconfig or bluetoothd during startup, forwarded to Chronicle and normalized as PROCESS_LAUNCH events in UDM.
Other platforms for T1011.001
Testing Methodology
Validate this detection against 5 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 1Enumerate Bluetooth Devices on Windows
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe and CommandLine containing 'Get-PnpDevice' and 'Bluetooth'. PowerShell ScriptBlock Log Event ID 4104 with the full enumeration command. No registry modification events, but PnpDevice queries may appear in Windows Plug and Play logs.
- Test 2Linux Bluetooth Device Scan with hcitool
Expected signal: Linux auditd: execve syscall for hcitool with arguments 'scan' and 'lescan'. Syslog/daemon.log: bluetoothd activity logs showing scan initiation. If auditd is configured with execve monitoring: type=EXECVE msg= records with a0='hcitool' a1='scan'. Sysmon for Linux Event ID 1 if deployed.
- Test 3Transfer File via OBEX over Bluetooth on Linux
Expected signal: Linux auditd/Sysmon: execve event for obexftp with arguments including '--bluetooth', a MAC address, and '--put' with the file path. File creation event for /tmp/bt_test_exfil.txt. The process will exit with an error but telemetry is generated. Syslog may show bluetoothd connection attempt to the specified MAC address.
- Test 4Python Bluetooth Exfiltration Script Execution (Windows/Linux)
Expected signal: Sysmon Event ID 1: Process Create for python3.exe or python.exe with CommandLine referencing Bluetooth. Child process creation: powershell.exe spawned by python with 'Get-PnpDevice -Class Bluetooth'. Sysmon Event ID 1 for the child powershell.exe. PowerShell ScriptBlock Log Event ID 4104 for the enumeration command.
- Test 5Bluetooth Registry Key Inspection for Paired Devices
Expected signal: Sysmon Event ID 1: Process Create for reg.exe with query arguments targeting BTHPORT. If PowerShell fallback executes: Sysmon Event ID 1 for powershell.exe with BTHPORT in CommandLine. Sysmon Event ID 12 (Registry key access) for HKLM\SYSTEM\CurrentControlSet\Services\BTHPORT\Parameters\Devices. PowerShell ScriptBlock Log Event ID 4104.
References (10)
- https://attack.mitre.org/techniques/T1011/001/
- https://attack.mitre.org/software/S0143/
- https://securelist.com/the-flame-questions-and-answers/34344/
- https://docs.microsoft.com/en-us/windows-hardware/drivers/bluetooth/bluetooth-host-radio-support
- https://www.bluetooth.com/learn-about-bluetooth/tech-overview/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1011.001/T1011.001.md
- https://learn.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/interactive-logon-do-not-require-ctrl-alt-del
- https://www.stigviewer.com/stig/windows_10/2021-08-18/finding/V-220843
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceregistryevents-table
- https://www.sans.org/white-papers/bluetooth-security-overview/
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