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https://github.com/splunk/security_content
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Eric
79 lines
3.7 KiB
YAML
79 lines
3.7 KiB
YAML
name: Linux Auditd Setuid Using Chmod Utility
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id: 8230c407-1b47-4d95-ac2e-718bd6381386
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version: 6
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date: '2025-05-02'
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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 chmod utility to
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set the SUID or SGID bit on files, which can allow users to temporarily gain root
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or group-level access. This detection leverages data from Linux Auditd, focusing
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on process names and command-line arguments related to chmod. This activity is significant
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as it can indicate an attempt to escalate privileges or maintain persistence on
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a system. If confirmed malicious, an attacker could gain elevated access, potentially
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compromising sensitive data or critical system functions.
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data_source:
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- Linux Auditd Proctitle
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search: '`linux_auditd` proctitle IN ("*chmod *") AND proctitle IN ("* u+s *", "* g+s *", "* 4777 *", "* 4577 *")
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| rename host as dest
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| stats count min(_time) as firstTime max(_time) as lastTime by proctitle dest
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| `security_content_ctime(firstTime)`
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|`security_content_ctime(lastTime)`
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| `linux_auditd_setuid_using_chmod_utility_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 execute this command.
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Please update the filter macros to remove false positives.
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references:
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- https://www.hackingarticles.in/linux-privilege-escalation-using-capabilities/
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drilldown_searches:
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- name: View the detection results for - "$dest$"
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search: '%original_detection_search% | search dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$dest$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$")
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starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime
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values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories)
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as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic)
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as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: A [$proctitle$] event occurred on host - [$dest$] to set the SUID or
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SGID bit on files using the chmod utility.
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risk_objects:
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- field: dest
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type: system
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score: 81
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threat_objects: []
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tags:
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analytic_story:
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- Linux Living Off The Land
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- Linux Privilege Escalation
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- Linux Persistence Techniques
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- Compromised Linux Host
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asset_type: Endpoint
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mitre_attack_id:
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- T1548.001
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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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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:
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https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1548.001/linux_auditd_setuid/auditd_proctitle_setuid.log
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source: auditd
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sourcetype: auditd
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