Suspicious System Commands Executed by Previously Unknown Executable

This rule monitors for the execution of several commonly used system commands executed by a previously unknown executable located in commonly abused directories. An alert from this rule can indicate the presence of potentially malicious activity, such as the execution of unauthorized or suspicious processes attempting to run malicious code. Detecting and investigating such behavior can help identify and mitigate potential security threats, protecting the system and its data from potential compromise.

Elastic rule (View on GitHub)

 1[metadata]
 2creation_date = "2023/06/14"
 3integration = ["endpoint"]
 4maturity = "production"
 5updated_date = "2024/05/21"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10This rule monitors for the execution of several commonly used system commands executed by a previously unknown
11executable located in commonly abused directories. An alert from this rule can indicate the presence of potentially
12malicious activity, such as the execution of unauthorized or suspicious processes attempting to run malicious code.
13Detecting and investigating such behavior can help identify and mitigate potential security threats, protecting the
14system and its data from potential compromise.
15"""
16from = "now-9m"
17index = ["logs-endpoint.events.*", "endgame-*"]
18language = "kuery"
19license = "Elastic License v2"
20name = "Suspicious System Commands Executed by Previously Unknown Executable"
21risk_score = 21
22rule_id = "e9001ee6-2d00-4d2f-849e-b8b1fb05234c"
23setup = """## Setup
24
25This rule requires data coming in from Elastic Defend.
26
27### Elastic Defend Integration Setup
28Elastic 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.
29
30#### Prerequisite Requirements:
31- Fleet is required for Elastic Defend.
32- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
33
34#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
35- Go to the Kibana home page and click "Add integrations".
36- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
37- Click "Add Elastic Defend".
38- Configure the integration name and optionally add a description.
39- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
40- 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).
41- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
42- 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.
43For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
44- Click "Save and Continue".
45- 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.
46For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
47"""
48severity = "low"
49tags = [
50    "Domain: Endpoint",
51    "OS: Linux",
52    "Use Case: Threat Detection",
53    "Tactic: Execution",
54    "Data Source: Elastic Endgame",
55    "Data Source: Elastic Defend",
56]
57timestamp_override = "event.ingested"
58type = "new_terms"
59
60query = '''
61host.os.type:linux and event.category:process and event.action:(exec or exec_event or fork or fork_event) and 
62process.executable:(
63  /bin/* or /usr/bin/* or /usr/share/* or /tmp/* or /var/tmp/* or /dev/shm/* or
64  /etc/init.d/* or /etc/rc*.d/* or /etc/crontab or /etc/cron.*/* or /etc/update-motd.d/* or 
65  /usr/lib/update-notifier/* or /home/*/.* or /boot/* or /srv/* or /run/*) 
66  and process.args:(whoami or id or hostname or uptime or top or ifconfig or netstat or route or ps or pwd or ls) and 
67  not process.name:(sudo or which or whoami or id or hostname or uptime or top or netstat or ps or pwd or ls or apt or 
68  dpkg or yum or rpm or dnf or dockerd or docker or snapd or snap) and
69  not process.parent.executable:(/bin/* or /usr/bin/* or /run/k3s/* or /etc/network/* or /opt/Elastic/*)
70'''
71
72
73[[rule.threat]]
74framework = "MITRE ATT&CK"
75[[rule.threat.technique]]
76id = "T1059"
77name = "Command and Scripting Interpreter"
78reference = "https://attack.mitre.org/techniques/T1059/"
79[[rule.threat.technique.subtechnique]]
80id = "T1059.004"
81name = "Unix Shell"
82reference = "https://attack.mitre.org/techniques/T1059/004/"
83
84
85
86[rule.threat.tactic]
87id = "TA0002"
88name = "Execution"
89reference = "https://attack.mitre.org/tactics/TA0002/"
90
91[rule.new_terms]
92field = "new_terms_fields"
93value = ["host.id", "user.id", "process.executable"]
94[[rule.new_terms.history_window_start]]
95field = "history_window_start"
96value = "now-14d"

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