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P4T12ICK
77 lines
3.2 KiB
YAML
77 lines
3.2 KiB
YAML
name: Windows Defacement Modify Transcodedwallpaper File
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id: e11c3d90-5bc7-42ad-94cd-ba75db10d897
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version: 1
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date: '2022-08-25'
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author: Teoderick Contreras, Splunk
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status: production
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type: Anomaly
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description: The following analytic identifies a modification to the Transcodedwallpaper
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file in the wallpaper theme directory to change the wallpaper of the host machine.
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This technique was seen in adversaries attempting to deface or change the desktop
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wallpaper of the targeted host. During our testing, the common process that affects
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or changes the wallpaper if a user changes it via desktop personalized setting is
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explorer.exe.
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data_source:
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- Sysmon Event ID 1
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search: '| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
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where Processes.process_path !="*\\Windows\\Explorer.EXE" by _time span=1h Processes.process_id
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Processes.process_name Processes.process Processes.dest Processes.process_guid Processes.original_file_name
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| `drop_dm_object_name(Processes)` |rename process_guid as proc_guid | join proc_guid,
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_time [ | tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Filesystem
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where Filesystem.file_path = "*\\AppData\\Roaming\\Microsoft\\Windows\\Themes\\TranscodedWallpaper"
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by _time span=1h Filesystem.dest Filesystem.file_create_time Filesystem.file_name
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Filesystem.file_path Filesystem.process_guid | `drop_dm_object_name(Filesystem)`
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|rename process_guid as proc_guid | fields file_name file_path process_name process_path
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process dest file_create_time _time proc_guid] | `windows_defacement_modify_transcodedwallpaper_file_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Filesystem` node. In addition,
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confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
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endpoint product.
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known_false_positives: 3rd part software application can change the wallpaper. Filter
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is needed.
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references:
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- https://forums.ivanti.com/s/article/Wallpaper-Windows-Settings-Desktop-Settings-and-the-transcodedwallpaper-jpg?language=en_US
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- https://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/ransom_sifreli.a
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tags:
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analytic_story:
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- Brute Ratel C4
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asset_type: Endpoint
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confidence: 30
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impact: 30
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message: modification or creation of transcodedwallpaper file by $process_name$
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in $dest$
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mitre_attack_id:
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- T1491
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observable:
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- name: dest
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type: Hostname
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role:
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- Victim
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- name: process_name
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type: Process
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role:
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- Attacker
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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required_fields:
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- _time
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- dest
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- file_create_time
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- file_name
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- file_path
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- process_name
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- process_path
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- process
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risk_score: 9
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/brute_ratel/wallpaper_via_transcodedwallpaper/sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: xmlwineventlog
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update_timestamp: true
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