Potential Reverse Shell via Suspicious Binary

  1[metadata]
  2creation_date = "2023/07/05"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/05/21"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10This detection rule detects the creation of a shell through a chain consisting of the execution of a suspicious binary
 11(located in a commonly abused location or executed manually) followed by a network event and ending with a shell being
 12spawned. Stageless reverse tcp shells display this behaviour. Attackers may spawn reverse shells to establish
 13persistence onto a target system.
 14"""
 15from = "now-9m"
 16index = ["logs-endpoint.events.*"]
 17language = "eql"
 18license = "Elastic License v2"
 19name = "Potential Reverse Shell via Suspicious Binary"
 20references = [
 21    "https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/Reverse%20Shell%20Cheatsheet.md",
 22]
 23risk_score = 47
 24rule_id = "fa3a59dc-33c3-43bf-80a9-e8437a922c7f"
 25setup = """## Setup
 26
 27This rule requires data coming in from Elastic Defend.
 28
 29### Elastic Defend Integration Setup
 30Elastic Defend is integrated into the Elastic Agent using Fleet. Upon configuration, the integration allows the Elastic Agent to monitor events on your host and send data to the Elastic Security app.
 31
 32#### Prerequisite Requirements:
 33- Fleet is required for Elastic Defend.
 34- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
 35
 36#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
 37- Go to the Kibana home page and click "Add integrations".
 38- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
 39- Click "Add Elastic Defend".
 40- Configure the integration name and optionally add a description.
 41- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
 42- Select a configuration preset. Each preset comes with different default settings for Elastic Agent, you can further customize these later by configuring the Elastic Defend integration policy. [Helper guide](https://www.elastic.co/guide/en/security/current/configure-endpoint-integration-policy.html).
 43- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
 44- Enter a name for the agent policy in "New agent policy name". If other agent policies already exist, you can click the "Existing hosts" tab and select an existing policy instead.
 45For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
 46- Click "Save and Continue".
 47- To complete the integration, select "Add Elastic Agent to your hosts" and continue to the next section to install the Elastic Agent on your hosts.
 48For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
 49"""
 50severity = "medium"
 51tags = [
 52    "Domain: Endpoint",
 53    "OS: Linux",
 54    "Use Case: Threat Detection",
 55    "Tactic: Execution",
 56    "Data Source: Elastic Defend",
 57]
 58type = "eql"
 59
 60query = '''
 61sequence by host.id, process.entity_id with maxspan=1s
 62[ process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
 63  process.executable : (
 64  "./*", "/tmp/*", "/var/tmp/*", "/var/www/*", "/dev/shm/*", "/etc/init.d/*", "/etc/rc*.d/*",
 65  "/etc/crontab", "/etc/cron.*", "/etc/update-motd.d/*", "/usr/lib/update-notifier/*",
 66  "/boot/*", "/srv/*", "/run/*", "/root/*", "/etc/rc.local"
 67   ) and
 68  process.parent.name : ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and not
 69  process.name : ("curl", "wget", "ping", "apt", "dpkg", "yum", "rpm", "dnf", "dockerd") ]
 70[ network where host.os.type == "linux" and event.type == "start" and event.action in ("connection_attempted", "connection_accepted") and
 71  process.executable : (
 72  "./*", "/tmp/*", "/var/tmp/*", "/var/www/*", "/dev/shm/*", "/etc/init.d/*", "/etc/rc*.d/*",
 73  "/etc/crontab", "/etc/cron.*", "/etc/update-motd.d/*", "/usr/lib/update-notifier/*",
 74  "/boot/*", "/srv/*", "/run/*", "/root/*", "/etc/rc.local"
 75   ) and destination.ip != null and destination.ip != "127.0.0.1" and destination.ip != "::1" ]
 76[ process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and 
 77  process.name : ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and 
 78  process.parent.name : ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") ]
 79'''
 80
 81
 82[[rule.threat]]
 83framework = "MITRE ATT&CK"
 84[[rule.threat.technique]]
 85id = "T1059"
 86name = "Command and Scripting Interpreter"
 87reference = "https://attack.mitre.org/techniques/T1059/"
 88[[rule.threat.technique.subtechnique]]
 89id = "T1059.004"
 90name = "Unix Shell"
 91reference = "https://attack.mitre.org/techniques/T1059/004/"
 92
 93
 94
 95[rule.threat.tactic]
 96id = "TA0002"
 97name = "Execution"
 98reference = "https://attack.mitre.org/tactics/TA0002/"
 99[[rule.threat]]
100framework = "MITRE ATT&CK"
101[[rule.threat.technique]]
102id = "T1071"
103name = "Application Layer Protocol"
104reference = "https://attack.mitre.org/techniques/T1071/"
105
106
107[rule.threat.tactic]
108id = "TA0011"
109name = "Command and Control"
110reference = "https://attack.mitre.org/tactics/TA0011/"