Potential Reverse Shell via Java

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This detection rule identifies the execution of a Linux shell process from a Java JAR application post an incoming network connection. This behavior may indicate reverse shell activity via a Java application.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Endpoint
  • OS: Linux
  • Use Case: Threat Detection
  • Tactic: Execution
  • Data Source: Elastic Defend

Version: 7

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

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sequence by host.id with maxspan=5s
  [network where host.os.type == "linux" and event.action in ("connection_accepted", "connection_attempted") and
   process.executable : ("/usr/bin/java", "/bin/java", "/usr/lib/jvm/*", "/usr/java/*") and
   not (destination.ip == null or destination.ip == "0.0.0.0" or cidrmatch(
     destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24", "192.0.0.0/29",
     "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32", "192.0.2.0/24",
     "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4", "100.64.0.0/10",
     "192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1", "FE80::/10",
     "FF00::/8"
    )
  )] by process.entity_id
  [process where host.os.type == "linux" and event.action == "exec" and
   process.parent.executable : ("/usr/bin/java", "/bin/java", "/usr/lib/jvm/*", "/usr/java/*") and
   process.parent.args : "-jar" and process.name in ("bash", "dash", "ash", "sh", "tcsh", "csh", "zsh", "ksh", "fish")
   and not process.parent.args in (
     "/usr/share/java/jenkins.war", "/etc/remote-iot/services/remoteiot.jar",
     "/usr/lib64/NetExtender.jar", "/usr/lib/jenkins/jenkins.war"
   )] by process.parent.entity_id

Framework: MITRE ATT&CKTM