Detection: Shai-Hulud Workflow File Creation or Modification

Updated Date: 2025-11-25 ID: 6b4a0a7f-10d1-4d72-9c4c-5c6a3d9f9d6a Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

Detects creation or deletion of malicious GitHub Actions workflow files associated with Shai-Hulud worm variants on Linux or Windows endpoints. This includes the original shai-hulud-workflow.yml, the 2.0 backdoor discussion.yaml (enables command injection via GitHub Discussions on self-hosted runners named SHA1HULUD), and the secrets exfiltration workflow formatter_*.yml pattern. These files are used to exfiltrate credentials and propagate across repositories.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
 3
 4from datamodel=Endpoint.Filesystem where
 5
 6Filesystem.file_path IN (
 7  "*/.github/workflows/discussion.yaml",
 8  "*/.github/workflows/discussion.yml",
 9  "*/.github/workflows/formatter_*.yaml",
10  "*/.github/workflows/formatter_*.yml",
11  "*/.github/workflows/shai-hulud-workflow.yaml",
12  "*/.github/workflows/shai-hulud-workflow.yml",
13  "*/.github/workflows/shai-hulud.yaml",
14  "*/.github/workflows/shai-hulud.yml",
15  "*\\.github\\workflows\\discussion.yaml",
16  "*\\.github\\workflows\\discussion.yml",
17  "*\\.github\\workflows\\formatter_*.yaml",
18  "*\\.github\\workflows\\formatter_*.yml",
19  "*\\.github\\workflows\\shai-hulud-workflow.yaml",
20  "*\\.github\\workflows\\shai-hulud-workflow.yml",
21  "*\\.github\\workflows\\shai-hulud.yaml",
22  "*\\.github\\workflows\\shai-hulud.yml"
23)
24
25by Filesystem.action Filesystem.dest Filesystem.file_access_time Filesystem.file_create_time
26   Filesystem.file_hash Filesystem.file_modify_time Filesystem.file_name Filesystem.file_path Filesystem.file_acl Filesystem.file_size Filesystem.process_guid Filesystem.process_id Filesystem.user
27   Filesystem.vendor_product
28
29
30| `drop_dm_object_name(Filesystem)`
31
32| `security_content_ctime(firstTime)`
33
34| `security_content_ctime(lastTime)`
35
36| `shai_hulud_workflow_file_creation_or_modification_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 11	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Sysmon for Linux EventID 11	Linux	`'sysmon:linux'`	`'Syslog:Linux-Sysmon/Operational'`

Macros Used

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

shai_hulud_workflow_file_creation_or_modification_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
T1574.006	Dynamic Linker Hijacking	Defense Evasion
T1554	Compromise Host Software Binary	Persistence
T1195	Supply Chain Compromise	Privilege Escalation

Delivery

Exploitation

Installation

DE.CM

CIS 10

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 Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain filesystem events, specifically file creation and deletion events. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Filesystem node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Very low. Legitimate usage of a file with this exact name is unlikely; validate with repository owners.

Associated Analytic Story

NPM Supply Chain Compromise

Risk Based Analytics (RBA)

Risk Message:

Shai-Hulud malicious workflow file detected on endpoint $dest$ at $file_path$. Immediate investigation required.

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	30	file_path

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`Syslog:Linux-Sysmon/Operational`	`sysmon:linux`
Integration	✅ Passing	Dataset	`Syslog:Linux-Sysmon/Operational`	`sysmon:linux`

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