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" 5min_stack_comments = "Multiple field support in the New Terms rule type was added in Elastic 8.6" 6min_stack_version = "8.6.0" 7updated_date = "2023/11/02" 8 9[rule] 10author = ["Elastic"] 11description = """ 12This rule monitors for the execution of several commonly used system commands executed by a previously unknown 13executable located in commonly abused directories. An alert from this rule can indicate the presence of potentially 14malicious activity, such as the execution of unauthorized or suspicious processes attempting to run malicious code. 15Detecting and investigating such behavior can help identify and mitigate potential security threats, protecting the 16system and its data from potential compromise. 17""" 18from = "now-9m" 19index = ["logs-endpoint.events.*", "endgame-*"] 20language = "kuery" 21license = "Elastic License v2" 22name = "Suspicious System Commands Executed by Previously Unknown Executable" 23risk_score = 21 24rule_id = "e9001ee6-2d00-4d2f-849e-b8b1fb05234c" 25setup = """ 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 50""" 51severity = "low" 52tags = ["Domain: Endpoint", "OS: Linux", "Use Case: Threat Detection", "Tactic: Execution", "Data Source: Elastic Endgame", "Data Source: Elastic Defend"] 53timestamp_override = "event.ingested" 54type = "new_terms" 55 56query = ''' 57host.os.type:linux and event.category:process and event.action:(exec or exec_event or fork or fork_event) and 58process.executable:( 59 /bin/* or /usr/bin/* or /usr/share/* or /tmp/* or /var/tmp/* or /dev/shm/* or 60 /etc/init.d/* or /etc/rc*.d/* or /etc/crontab or /etc/cron.*/* or /etc/update-motd.d/* or 61 /usr/lib/update-notifier/* or /home/*/.* or /boot/* or /srv/* or /run/*) 62 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 63 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 64 dpkg or yum or rpm or dnf or dockerd or docker or snapd or snap) and 65 not process.parent.executable:(/bin/* or /usr/bin/* or /run/k3s/* or /etc/network/* or /opt/Elastic/*) 66''' 67 68[[rule.threat]] 69framework = "MITRE ATT&CK" 70 71[rule.threat.tactic] 72name = "Execution" 73id = "TA0002" 74reference = "https://attack.mitre.org/tactics/TA0002/" 75 76[[rule.threat.technique]] 77name = "Command and Scripting Interpreter" 78id = "T1059" 79reference = "https://attack.mitre.org/techniques/T1059/" 80 81[[rule.threat.technique.subtechnique]] 82name = "Unix Shell" 83id = "T1059.004" 84reference = "https://attack.mitre.org/techniques/T1059/004/" 85 86[rule.new_terms] 87field = "new_terms_fields" 88value = ["host.id", "user.id", "process.executable"] 89 90[[rule.new_terms.history_window_start]] 91field = "history_window_start" 92value = "now-14d"
- BPF filter applied using TC
- Binary Executed from Shared Memory Directory
- Cron Job Created or Changed by Previously Unknown Process
- Interactive Terminal Spawned via Perl
- Interactive Terminal Spawned via Python