Detection rules › Splunk
Windows Office Product Loading Taskschd DLL
The following analytic detects an Office document creating a scheduled task, either through a macro VBA API or by loading taskschd.dll. This detection leverages Sysmon EventCode 7 to identify when Office applications load the taskschd.dll file. This activity is significant as it is a common technique used by malicious macro malware to establish persistence or initiate beaconing. If confirmed malicious, this could allow an attacker to maintain persistence, execute arbitrary commands, or schedule future malicious activities, posing a significant threat to the environment.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566.001 Phishing: Spearphishing Attachment |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 7 | Image loaded |
Rule body splunk
name: Windows Office Product Loading Taskschd DLL
id: d7297cfa-1f04-4714-bfbe-3679e0666959
version: 7
creation_date: '2021-04-14'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects an Office document creating a scheduled task, either through a macro VBA API or by loading `taskschd.dll`. This detection leverages Sysmon EventCode 7 to identify when Office applications load the `taskschd.dll` file. This activity is significant as it is a common technique used by malicious macro malware to establish persistence or initiate beaconing. If confirmed malicious, this could allow an attacker to maintain persistence, execute arbitrary commands, or schedule future malicious activities, posing a significant threat to the environment.
data_source:
- Sysmon EventID 7
search: '`sysmon` EventCode=7 process_name IN ("EQNEDT32.exe", "excel.exe", "Graph.exe", "msaccess.exe", "mspub.exe", "onenote.exe", "onenoteim.exe", "onenotem.exe", "outlook.exe", "powerpnt.exe", "visio.exe", "winproj.exe", "winword.exe") loaded_file_path = "*\\taskschd.dll" | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded dest loaded_file loaded_file_path original_file_name process_exec process_guid process_hash process_id process_name process_path service_dll_signature_exists service_dll_signature_verified signature signature_id user_id vendor_product | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_office_product_loading_taskschd_dll_filter`'
how_to_implement: To successfully implement this search, you need to be ingesting logs with the process name and ImageLoaded (Like sysmon EventCode 7) from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Also be sure to include those monitored dll to your own sysmon config.
known_false_positives: False positives may occur if legitimate office documents are creating scheduled tasks. Ensure to investigate the scheduled task and the command to be executed. If the task is benign, add the task name to the exclusion list. Some applications may legitimately load taskschd.dll.
references:
- https://research.checkpoint.com/2021/irans-apt34-returns-with-an-updated-arsenal/
- https://redcanary.com/threat-detection-report/techniques/scheduled-task-job/
- https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/trojanized-onenote-document-leads-to-formbook-malware/
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: An Office document was identified creating a scheduled task on $dest$. Investigate further.
analytic_story:
- Spearphishing Attachments
asset_type: Endpoint
mitre_attack_id:
- T1566.001
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/attack_techniques/T1566.001/datasets/windows-sysmon.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: XmlWinEventLog
test_type: unit
Stages and Predicates
Stage 1: search
`sysmon` EventCode=7 process_name IN ("EQNEDT32.exe", "excel.exe", "Graph.exe", "msaccess.exe", "mspub.exe", "onenote.exe", "onenoteim.exe", "onenotem.exe", "outlook.exe", "powerpnt.exe", "visio.exe", "winproj.exe", "winword.exe") loaded_file_path = "*\\taskschd.dll"
Stage 2: fillnull
| fillnull
Stage 3: stats
| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded dest loaded_file loaded_file_path original_file_name process_exec process_guid process_hash process_id process_name process_path service_dll_signature_exists service_dll_signature_verified signature signature_id user_id vendor_product
Stage 4: search
| `security_content_ctime(firstTime)`
Stage 5: search
| `security_content_ctime(lastTime)`
Stage 6: search
| `windows_office_product_loading_taskschd_dll_filter`
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.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
loaded_file_path | eq |
|
process_name | in |
|