Detection: Splunk XSS in Highlighted JSON Events

Updated Date: 2024-10-17 ID: 1030bc63-0b37-4ac9-9ae0-9361c955a3cc Author: Rod Soto, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies potential exploitation of a Cross-Site Scripting (XSS) vulnerability in Splunk Enterprise 9.1.2. It detects suspicious requests to the Splunk web GUI that may execute JavaScript within script tags. This detection leverages logs from the splunkd_ui data source, focusing on specific URI paths and HTTP methods. This activity is significant as it can allow attackers to execute arbitrary JavaScript, potentially accessing the API with the logged-in user's permissions. If the user is an admin, the attacker could create an admin account, leading to full control over the Splunk environment.

1`splunkd_ui` "/*/splunkd/__raw/servicesNS/nobody/search/authentication/users" status=201 
2| stats count min(_time) as firstTime max(_time) as lastTime by clientip, uri_path, method 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `splunk_xss_in_highlighted_json_events_filter`

Data Source

Name Platform Sourcetype Source
Splunk Splunk icon Splunk 'splunkd_ui_access' 'splunkd_ui_access.log'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
splunk_xss_in_highlighted_json_events_filter search *
splunk_xss_in_highlighted_json_events_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
T1189 Drive-by Compromise Initial Access
KillChainPhase.DELIVERY
NistCategory.DE_AE
Cis18Value.CIS_10
APT19
APT28
APT32
APT37
APT38
Andariel
Axiom
BRONZE BUTLER
CURIUM
Daggerfly
Dark Caracal
Darkhotel
Dragonfly
Earth Lusca
Elderwood
Lazarus Group
Leafminer
Leviathan
Machete
Magic Hound
Mustard Tempest
PLATINUM
PROMETHIUM
Patchwork
RTM
Threat Group-3390
Transparent Tribe
Turla
Windigo
Windshift
Winter Vivern

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 Risk Event False
This configuration file applies to all detections of type hunting.

Implementation

This search only applies to web-GUI-enabled Splunk instances and operator must have access to internal indexes.

Known False Positives

This is a hunting search and will produce false positives as it is not possible to view contents of a request payload. It shows the artifact resulting from a potential exploitation payload (the creation of a user with admin privileges).

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Possible XSS exploitation from $clientip$ 15 30 50
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 splunkd_ui_access.log splunkd_ui_access
Integration ✅ Passing Dataset splunkd_ui_access.log splunkd_ui_access

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