Detection: Outbound Network Connection from Java Using Default Ports

Updated Date: 2026-02-25 ID: d2c14d28-5c47-11ec-9892-acde48001122 Author: Mauricio Velazco, Lou Stella, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects outbound network connections from Java processes to default ports used by LDAP and RMI protocols, which may indicate exploitation of the CVE-2021-44228-Log4j vulnerability. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and network traffic logs. Monitoring this activity is crucial as it can signify an attacker’s attempt to perform JNDI lookups and retrieve malicious payloads. If confirmed malicious, this activity could lead to remote code execution and further compromise of the affected server.

Search

 1
 2| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
 3  WHERE (
 4        Processes.process_name="java.exe"
 5        OR
 6        Processes.process_name=javaw.exe
 7        OR
 8        Processes.process_name=javaw.exe
 9    )
10  BY Processes.action Processes.dest Processes.original_file_name
11     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
12     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
13     Processes.process Processes.process_exec Processes.process_guid
14     Processes.process_hash Processes.process_id Processes.process_integrity_level
15     Processes.process_name Processes.process_path Processes.user
16     Processes.user_id Processes.vendor_product
17
18| `drop_dm_object_name(Processes)`
19
20| `security_content_ctime(firstTime)`
21
22| `security_content_ctime(lastTime)`
23
24| join process_id [
25
26| tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic
27  WHERE (
28        All_Traffic.dest_port= 389
29        OR
30        All_Traffic.dest_port= 636
31        OR
32        All_Traffic.dest_port = 1389
33        OR
34        All_Traffic.dest_port = 1099
35    )
36  BY All_Traffic.action All_Traffic.app All_Traffic.bytes
37     All_Traffic.bytes_in All_Traffic.bytes_out All_Traffic.dest
38     All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc
39     All_Traffic.protocol All_Traffic.protocol_version All_Traffic.src
40     All_Traffic.src_ip All_Traffic.src_port All_Traffic.transport
41     All_Traffic.user All_Traffic.vendor_product All_Traffic.direction
42     All_Traffic.process_id
43
44| `drop_dm_object_name(All_Traffic)`
45
46| rename dest as connection_to_CNC]
47
48| table _time dest parent_process_name process_name process_path process dest_port
49
50| `outbound_network_connection_from_java_using_default_ports_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 1	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Sysmon EventID 3	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

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

outbound_network_connection_from_java_using_default_ports_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
T1190	Exploit Public-Facing Application	Initial Access
T1133	External Remote Services	Initial Access

Delivery

Installation

DE.CM

CIS 10

CVE

CVE-2021-44228

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 the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. 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 Processes 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

Legitimate Java applications may use perform outbound connections to these ports. Filter as needed

Associated Analytic Story

Log4Shell CVE-2021-44228

Risk Based Analytics (RBA)

Risk Message:

Java performed outbound connections to default ports of LDAP or RMI on $dest$

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	54	No Threat Objects

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

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: 9