Linux Auditd Find Ssh Private Keys

name: Linux Auditd Find Ssh Private Keys
id: e2d2bd10-dcd1-4b2f-8a76-0198eab32ba5
version: 11
creation_date: '2024-08-12'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects suspicious attempts to find SSH private keys, which may indicate an attacker's effort to compromise secure access to systems. SSH private keys are essential for secure authentication, and unauthorized access to these keys can enable attackers to gain unauthorized access to servers and other critical infrastructure. By monitoring for unusual or unauthorized searches for SSH private keys, this analytic helps identify potential threats to network security, allowing security teams to quickly respond and safeguard against unauthorized access and potential breaches.
data_source:
    - Linux Auditd Execve
search: |-
    `linux_auditd` execve_command IN ("*find*", "*grep*") AND execve_command IN ("*id_rsa*", "*id_dsa*", "*.key*", "*ssh_key*", "*authorized_keys*")
      | rename host as dest
      | rename comm as process_name
      | rename exe as process
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY argc execve_command dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `linux_auditd_find_ssh_private_keys_filter`
how_to_implement: To implement this detection, the process begins by ingesting auditd data, that consists of SYSCALL, TYPE, EXECVE and PROCTITLE events, which captures command-line executions and process details on Unix/Linux systems. These logs should be ingested and processed using Splunk Add-on for Unix and Linux (https://splunkbase.splunk.com/app/833), which is essential for correctly parsing and categorizing the data. The next step involves normalizing the field names  to match the field names set by the Splunk Common Information Model (CIM) to ensure consistency across different data sources and enhance the efficiency of data modeling. This approach enables effective monitoring and detection of linux endpoints where auditd is deployed
known_false_positives: Administrator or network operator can use this application for automation purposes. Please update the filter macros to remove false positives.
references:
    - https://www.splunk.com/en_us/blog/security/deep-dive-on-persistence-privilege-escalation-technique-and-detection-in-linux-platform.html
    - https://github.com/peass-ng/PEASS-ng/tree/master/linPEAS
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A [$execve_command$] event occurred on host - [$dest$] to find SSH private keys.
analytic_story:
    - Linux Living Off The Land
    - Linux Privilege Escalation
    - Linux Persistence Techniques
    - Compromised Linux Host
    - Hellcat Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1552.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint