Detection rules › Splunk
Windows Raw Access To Disk Volume Partition
The following analytic detects suspicious raw access reads to the device disk partition of a host machine. It leverages Sysmon EventCode 9 logs to identify processes attempting to read or write to the boot sector, excluding legitimate system processes. This activity is significant as it is commonly associated with destructive actions by adversaries, such as wiping, encrypting, or overwriting the boot sector, as seen in attacks involving malware like HermeticWiper. If confirmed malicious, this behavior could lead to severe impacts, including system inoperability, data loss, or compromised boot integrity.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Impact | T1561.002 Disk Wipe: Disk Structure Wipe |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 9 | RawAccessRead |
Rule body splunk
name: Windows Raw Access To Disk Volume Partition
id: a85aa37e-9647-11ec-90c5-acde48001122
version: 13
creation_date: '2022-02-25'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects suspicious raw access reads to the device disk partition of a host machine. It leverages Sysmon EventCode 9 logs to identify processes attempting to read or write to the boot sector, excluding legitimate system processes. This activity is significant as it is commonly associated with destructive actions by adversaries, such as wiping, encrypting, or overwriting the boot sector, as seen in attacks involving malware like HermeticWiper. If confirmed malicious, this behavior could lead to severe impacts, including system inoperability, data loss, or compromised boot integrity.
data_source:
- Sysmon EventID 9
search: '`sysmon` EventCode=9 Device = \\Device\\HarddiskVolume* NOT (Image IN("*\\Windows\\System32\\*", "*\\Windows\\SysWOW64\\*")) | stats count min(_time) as firstTime max(_time) as lastTime by dest dvc process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Device Image | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_raw_access_to_disk_volume_partition_filter`'
how_to_implement: To successfully implement this search, you need to be ingesting logs with the raw access read event (like sysmon eventcode 9), process name and process guid from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: There are som minimal number of normal applications from system32 folder like svchost.exe accessing the MBR. In this case we used 'system32' and 'syswow64' path as a filter for this detection.
references:
- https://blog.talosintelligence.com/2022/02/threat-advisory-hermeticwiper.html
drilldown_searches:
- name: View the detection results for - "$dest$"
search: '%original_detection_search% | search dest = "$dest$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$dest$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
intermediate_findings:
entities:
- field: dest
type: system
score: 20
message: Process accessing disk partition $Device$ on $dest$
analytic_story:
- CISA AA22-264A
- Graceful Wipe Out Attack
- Data Destruction
- Hermetic Wiper
- Caddy Wiper
- BlackByte Ransomware
- NjRAT
- Disk Wiper
- PathWiper
- Void Manticore
asset_type: Endpoint
mitre_attack_id:
- T1561.002
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/hermetic_wiper/sysmon.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: XmlWinEventLog
test_type: unit
Stages and Predicates
Stage 1: search
`sysmon` EventCode=9 Device = \\Device\\HarddiskVolume* NOT (Image IN("*\\Windows\\System32\\*", "*\\Windows\\SysWOW64\\*"))
Stage 2: stats
| stats count min(_time) as firstTime max(_time) as lastTime by dest dvc process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Device Image
Stage 3: search
| `security_content_ctime(firstTime)`
Stage 4: search
| `security_content_ctime(lastTime)`
Stage 5: search
| `windows_raw_access_to_disk_volume_partition_filter`
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Image | in | "*\\Windows\\SysWOW64\\*", "*\\Windows\\System32\\*" |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.