Detection: Azure Runbook Webhook Created

Updated Date: 2024-05-23 ID: e98944a9-92e4-443c-81b8-a322e33ce75a Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation of a new Automation Runbook Webhook within an Azure tenant. It leverages Azure Audit events, specifically the "Create or Update an Azure Automation webhook" operation, to identify this activity. This behavior is significant because Webhooks can trigger Automation Runbooks via unauthenticated URLs exposed to the Internet, posing a security risk. If confirmed malicious, an attacker could use this to execute code, create users, or maintain persistence within the environment, potentially leading to unauthorized access and control over Azure resources.

Search

1 `azure_audit` operationName.localizedValue="Create or Update an Azure Automation webhook" status.value=Succeeded 
2| dedup object 
3| rename claims.ipaddr as src_ip 
4| rename caller as user 
5| stats count min(_time) as firstTime max(_time) as lastTime by object user, src_ip, resourceGroupName, object_path 
6| `security_content_ctime(firstTime)` 
7| `security_content_ctime(lastTime)` 
8| `azure_runbook_webhook_created_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Azure Audit Create or Update an Azure Automation webhook	Azure	`'mscs:azure:audit'`	`'mscs:azure:audit'`	N/A

Macros Used

Name	Value
azure_audit	`sourcetype=mscs:azure:audit`
azure_runbook_webhook_created_filter	`search *`

azure_runbook_webhook_created_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
T1078	Valid Accounts	Defense Evasion
T1078.004	Cloud Accounts	Initial Access

KillChainPhase.DELIVERY

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

APT18

APT28

APT29

APT33

APT39

APT41

Akira

Axiom

Carbanak

Chimera

Cinnamon Tempest

Dragonfly

FIN10

FIN4

FIN5

FIN6

FIN7

FIN8

Fox Kitten

GALLIUM

Ke3chang

LAPSUS$

Lazarus Group

Leviathan

OilRig

POLONIUM

PittyTiger

Sandworm Team

Silence

Silent Librarian

Suckfly

Threat Group-3390

Wizard Spider

menuPass

APT28

APT29

APT33

APT5

Ke3chang

LAPSUS$

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

You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Audit events into your Splunk environment. Specifically, this analytic leverages the Azure Activity log category.

Known False Positives

Administrators may legitimately create Azure Runbook Webhooks. Filter as needed.

Associated Analytic Story

Azure Active Directory Persistence

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A new Azure Runbook Webhook $object$ was created by $user$	63	70	90

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`mscs:azure:audit`	`mscs:azure:audit`
Integration	✅ Passing	Dataset	`mscs:azure:audit`	`mscs:azure:audit`

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: 4