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76 lines
3.3 KiB
YAML
76 lines
3.3 KiB
YAML
name: Linux Auditd At Application Execution
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id: 9f306e0a-1c36-469e-8892-968ca12470dd
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version: 1
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date: '2024-09-04'
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author: Teoderick Contreras, Splunk
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status: production
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type: Anomaly
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description: The following analytic detects the execution of the "At" application
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in Linux, which can be used by attackers to create persistence entries on a compromised
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host. This detection leverages data from Endpoint Detection and Response (EDR) agents,
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focusing on process names and parent process names associated with "at" or "atd".
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This activity is significant because the "At" application can be exploited to maintain
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unauthorized access or deliver additional malicious payloads. If confirmed malicious,
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this behavior could lead to data theft, ransomware attacks, or other severe consequences.
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Immediate investigation is required to determine the legitimacy of the execution
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and mitigate potential risks.
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data_source:
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- Linux Auditd Syscall
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search: '`linux_auditd` type=SYSCALL comm IN ("at", "atd") OR exe IN ("/usr/bin/at","/usr/bin/atd")
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AND NOT (UID IN("daemon")) | rename host as dest | stats count min(_time) as firstTime
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max(_time) as lastTime by comm exe SYSCALL UID ppid pid dest | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)`| `linux_auditd_at_application_execution_filter`'
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how_to_implement: To implement this detection, the process begins by ingesting auditd
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data, that consist SYSCALL, TYPE, EXECVE and PROCTITLE events, which captures command-line
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executions and process details on Unix/Linux systems. These logs should be ingested
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and processed using Splunk Add-on for Unix and Linux (https://splunkbase.splunk.com/app/833),
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which is essential for correctly parsing and categorizing the data. The next step
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involves normalizing the field names to match the field names set by the Splunk
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Common Information Model (CIM) to ensure consistency across different data sources
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and enhance the efficiency of data modeling. This approach enables effective monitoring
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and detection of linux endpoints where auditd is deployed
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known_false_positives: Administrator or network operator can use this application
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for automation purposes. Please update the filter macros to remove false positives.
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references:
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- https://attack.mitre.org/techniques/T1053/001/
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- https://www.linkedin.com/pulse/getting-attacker-ip-address-from-malicious-linux-job-craig-rowland/
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tags:
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analytic_story:
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- Scheduled Tasks
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- Linux Privilege Escalation
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- Linux Persistence Techniques
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- Linux Living Off The Land
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- Compromised Linux Host
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asset_type: Endpoint
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confidence: 30
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impact: 30
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message: A SYSCALL - [$comm$] event was executed on host - [$dest$] to execute the "at" application.
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mitre_attack_id:
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- T1053.002
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- T1053
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observable:
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- name: dest
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type: Endpoint
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role:
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- Victim
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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required_fields:
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- _time
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- comm
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- exe
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- SYSCALL
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- UID
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- ppid
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- pid
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risk_score: 9
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1053.002/linux_auditd_at/linux_auditd_at_execution.log
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source: /var/log/audit/audit.log
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sourcetype: linux:audit
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