Linux Auditd Find Private Keys

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic has been deprecated. The following analytic detects suspicious attempts to find private keys, which may indicate an attacker's effort to access sensitive cryptographic information. Private keys are crucial for securing encrypted communications and data, and unauthorized access to them can lead to severe security breaches, including data decryption and identity theft. By monitoring for unusual or unauthorized searches for private keys, this analytic helps identify potential threats to cryptographic security, enabling security teams to take swift action to protect the integrity and confidentiality of encrypted information.

name: Linux Auditd Find Private Keys
id: 80bb9988-190b-4ee0-a3c3-509545a8f678
version: 6
creation_date: '2024-08-12'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: removed
type: TTP
description: The following analytic has been deprecated. The following analytic detects suspicious attempts to find private keys, which may indicate an attacker's effort to access sensitive cryptographic information. Private keys are crucial for securing encrypted communications and data, and unauthorized access to them can lead to severe security breaches, including data decryption and identity theft. By monitoring for unusual or unauthorized searches for private keys, this analytic helps identify potential threats to cryptographic security, enabling security teams to take swift action to protect the integrity and confidentiality of encrypted information.
data_source:
    - Linux Auditd Execve
search: '`linux_auditd` `linux_auditd_normalized_execve_process` | rename host as dest | where  (LIKE (process_exec, "%find%") OR LIKE (process_exec, "%grep%")) AND (LIKE (process_exec, "%.pem%") OR LIKE (process_exec, "%.cer%") OR LIKE (process_exec, "%.crt%") OR LIKE (process_exec, "%.pgp%") OR LIKE (process_exec, "%.key%") OR LIKE (process_exec, "%.gpg%")OR LIKE (process_exec, "%.ppk%") OR LIKE (process_exec, "%.p12%")OR LIKE (process_exec, "%.pfx%")OR LIKE (process_exec, "%.p7b%")) | stats count min(_time) as firstTime max(_time) as lastTime by argc process_exec dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| `linux_auditd_find_private_keys_filter`'
how_to_implement: To implement this detection, the process begins by ingesting auditd data, that consist 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
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A [$process_exec$] event occurred on host - [$dest$] to find private keys.
    risk_objects:
        - field: dest
          type: system
          score: 64
    threat_objects: []
tags:
    analytic_story:
        - Linux Living Off The Land
        - Linux Privilege Escalation
        - Linux Persistence Techniques
        - Compromised Linux Host
    asset_type: Endpoint
    mitre_attack_id:
        - T1552.004
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
          - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1552.004/linux_auditd_find_gpg/linux_auditd_find_gpg.log
            source: /var/log/audit/audit.log
            sourcetype: linux:audit
deprecation_info:
    reason: Renamed and updated logic
    removed_in_version: 5.2.0
    replacement_content:
        - Linux Auditd Private Keys and Certificate Enumeration

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9156a742-f158-42b8-b17e-e0b1ee44e95f

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