Detection: Outbound Network Connection from Java Using Default Ports

Updated Date: 2026-03-18 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
 3FROM datamodel=Endpoint.Processes WHERE
 4
 5Processes.process_name IN (
 6    "java.exe",
 7    "javaw.exe"
 8)
 9BY Processes.action Processes.dest Processes.original_file_name
10   Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
11   Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
12   Processes.process Processes.process_exec Processes.process_guid
13   Processes.process_hash Processes.process_id Processes.process_integrity_level
14   Processes.process_name Processes.process_path Processes.user
15   Processes.user_id Processes.vendor_product
16
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    
27| tstats `security_content_summariesonly` count
28    FROM datamodel=Network_Traffic.All_Traffic WHERE
29    All_Traffic.dest_port IN (
30                389,
31                636,
32                1099,
33                1389
34    )
35    BY All_Traffic.action All_Traffic.app All_Traffic.bytes
36        All_Traffic.bytes_in All_Traffic.bytes_out All_Traffic.dest
37        All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc
38        All_Traffic.protocol All_Traffic.protocol_version All_Traffic.src
39        All_Traffic.src_ip All_Traffic.src_port All_Traffic.transport
40        All_Traffic.user All_Traffic.vendor_product All_Traffic.direction
41        All_Traffic.process_id
42    
43| `drop_dm_object_name(All_Traffic)`
44    
45| rename dest as connection_to_CNC
46]
47
48| table _time dest
49        parent_process_path parent_process_name parent_process
50        process_path process_name process process_hash
51        connection_to_CNC dest_port user
52
53| `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	50	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: 11