splunk-security_content/docs/_posts/2022-02-16-windows_bitsadmin_download_file.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Windows Bitsadmin Download File	BITS Jobs, Ingress Tool Transfer	Endpoint	2022-02-16	true		BITS Jobs Defense Evasion Persistence Ingress Tool Transfer Command & Control Splunk Behavioral Analytics Endpoint_Processes

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Description

The following query identifies Microsoft Background Intelligent Transfer Service utility bitsadmin.exe using the transfer parameter to download a remote object. In addition, look for download or upload on the command-line, the switches are not required to perform a transfer. Capture any files downloaded. Review the reputation of the IP or domain used. Typically once executed, a follow on command will be used to execute the dropped file. Note that the network connection or file modification events related will not spawn or create from bitsadmin.exe, but the artifacts will appear in a parallel process of svchost.exe with a command-line similar to svchost.exe -k netsvcs -s BITS. It's important to review all parallel and child processes to capture any behaviors and artifacts. In some suspicious and malicious instances, BITS jobs will be created. You can use bitsadmin /list /verbose to list out the jobs during investigation.

• Type: TTP
• Product: Splunk Behavioral Analytics
• Datamodel: Endpoint_Processes
• Last Updated: 2022-02-16
• Author: Michael Haag, Splunk
• ID: d76e8188-8f5a-11ec-ace4-acde48001122

ATT&CK

ID	Technique	Tactic
T1197	BITS Jobs	Defense Evasion, Persistence

| T1105 | Ingress Tool Transfer | Command And Control |

Search

| from read_ssa_enriched_events() 
| where "Endpoint_Processes" IN(_datamodels) 
| eval timestamp=parse_long(ucast(map_get(input_event, "_time"), "string", null)), cmd_line=ucast(map_get(input_event, "process"), "string", null), process_name=ucast(map_get(input_event, "process_name"), "string", null), process_path=ucast(map_get(input_event, "process_path"), "string", null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string", null), event_id=ucast(map_get(input_event, "event_id"), "string", null) 
| where cmd_line IS NOT NULL AND process_name IS NOT NULL AND process_name="bitsadmin.exe" AND (like (cmd_line, "%transfer%")) 
| eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"), "string", null)) 
| eval body=create_map(["event_id", event_id, "cmd_line", cmd_line, "process_name", process_name, "parent_process_name", parent_process_name, "process_path", process_path]) 
| into write_ssa_detected_events();

Macros

The SPL above uses the following Macros:

Note that windows_bitsadmin_download_file_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

• _time
• dest_device_id
• process_name
• parent_process_name
• process_path
• dest_user_id
• process
• cmd_line

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

Limited false positives, however it may be required to filter based on parent process name or network connection.

Associated Analytic story

• Ingress Tool Transfer
• BITS Jobs
• DarkSide Ransomware
• Living Off The Land

Kill Chain Phase

• Exploitation

RBA

Risk Score	Impact	Confidence	Message
49.0	70	70	An instance of parent_process_name spawning process_name was identified on endpoint dest by user dest_user_id attempting to download a file.

Note that risk score is calculated base on the following formula: (Impact * Confidence)/100

Reference

• https://github.com/redcanaryco/atomic-red-team/blob/8eb52117b748d378325f7719554a896e37bccec7/atomics/T1105/T1105.md#atomic-test-9---windows---bitsadmin-bits-download
• https://github.com/redcanaryco/atomic-red-team/blob/bc705cb7aaa5f26f2d96585fac8e4c7052df0ff9/atomics/T1197/T1197.md
• https://docs.microsoft.com/en-us/windows/win32/bits/bitsadmin-tool
• https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/

Test Dataset

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1197/atomic_red_team/bits-windows-security.log

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