Log4Shell JNDI Payload Injection with Outbound Connection

name: Log4Shell JNDI Payload Injection with Outbound Connection
id: 69afee44-5c91-11ec-bf1f-497c9a704a72
version: 9
creation_date: '2021-12-13'
modification_date: '2026-05-13'
author: Jose Hernandez
status: production
type: Anomaly
description: The following analytic detects Log4Shell JNDI payload injections via outbound connections. It identifies suspicious LDAP lookup functions in web logs, such as `${jndi:ldap://PAYLOAD_INJECTED}`, and correlates them with network traffic to known malicious IP addresses. This detection leverages the Web and Network_Traffic data models in Splunk. Monitoring this activity is crucial as it targets vulnerabilities in Java web applications using log4j, potentially leading to remote code execution. If confirmed malicious, attackers could gain unauthorized access, execute arbitrary code, and compromise sensitive data within the affected environment.
data_source: []
search: |-
    | from datamodel Web.Web
    | rex field=_raw max_match=0 "[jJnNdDiI]{4}(\:|\%3A|\/|\%2F)(?<proto>\w+)(\:\/\/|\%3A\%2F\%2F)(\$\{.*?\}(\.)?)?(?<affected_host>[a-zA-Z0-9\.\-\_\$]+)" | join affected_host type=inner [| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Network_Traffic.All_Traffic by All_Traffic.dest | `drop_dm_object_name(All_Traffic)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | rename dest AS affected_host]
    | fillnull
    | stats count by action, category, dest, dest_port, http_content_type, http_method, http_referrer, http_user_agent, site, src, url, url_domain, user
    | `log4shell_jndi_payload_injection_with_outbound_connection_filter`
how_to_implement: This detection requires the Web datamodel to be populated from a supported Technology Add-On like Splunk for Apache or Splunk for Nginx.
known_false_positives: If there is a vulnerablility scannner looking for log4shells this will trigger, otherwise likely to have low false positives.
references:
    - https://www.lunasec.io/docs/blog/log4j-zero-day/
intermediate_findings:
    entities:
        - field: user
          type: user
          score: 20
          message: CVE-2021-44228 Log4Shell triggered for host $dest$
        - field: dest
          type: system
          score: 20
          message: CVE-2021-44228 Log4Shell triggered for host $dest$
analytic_story:
    - Log4Shell CVE-2021-44228
    - CISA AA22-320A
asset_type: Endpoint
cve:
    - CVE-2021-44228
mitre_attack_id:
    - T1190
    - T1133
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: web
security_domain: threat