Detection: Windows BitLockerToGo with Network Activity

Updated Date: 2024-11-13 ID: 14e3a089-cc23-4f4d-a770-26e44a31fbac Author: Michael Haag, Nasreddine Bencherchali, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects suspicious usage of BitLockerToGo.exe, which has been observed being abused by Lumma stealer malware. The malware leverages this legitimate Windows utility to manipulate registry keys, search for cryptocurrency wallets and credentials, and exfiltrate sensitive data. This activity is significant because BitLockerToGo.exe provides functionality for viewing, copying, and writing files as well as modifying registry branches - capabilities that the Lumma stealer exploits for malicious purposes. If confirmed malicious, this could indicate an active data theft campaign targeting cryptocurrency wallets, browser credentials, and password manager archives. The detection focuses on identifying BitLockerToGo.exe execution patterns that deviate from normal system behavior.

Search

1`sysmon` EventCode=22 process_name="bitlockertogo.exe" 
2| stats count min(_time) as firstTime max(_time) as lastTime values(query) as query values(answer) as answer values(QueryResults) as query_results values(QueryStatus) as query_status by process_name process_guid Computer 
3| rename Computer as dest 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_bitlockertogo_with_network_activity_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_bitlockertogo_with_network_activity_filter	`search *`

windows_bitlockertogo_with_network_activity_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1218	System Binary Proxy Execution	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

Lazarus Group

Volt Typhoon

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name and eventcode = 22 dnsquery executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

False positives are likely, as BitLockerToGo.exe is a legitimate Windows utility used for managing BitLocker encryption. However, the detection is designed to flag unusual execution patterns that deviate from standard usage. Filtering may be required to reduce false positives, once confirmed - move to TTP.

Associated Analytic Story

Lumma Stealer

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
BitLockerToGo.exe was executed with network activity on $dest$.	56	70	80

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1