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https://github.com/splunk/security_content
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Bhavin Patel
61 lines
2.2 KiB
YAML
61 lines
2.2 KiB
YAML
name: Linux At Allow Config File Creation
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id: 977b3082-5f3d-11ec-b954-acde48001122
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version: 1
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date: '2021-12-17'
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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 identifies a suspicious file creation of /etc/at.allow
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or /etc/at.deny. These 2 files are commonly abused by malware, adversaries or red
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teamers to persist on the targeted or compromised host. These config files can restrict
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or allow user to execute "at" application (another schedule task application in
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linux). attacker can create a user or add the compromised username to that config
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file to execute "at" to schedule it malicious code. This anomaly detection can be
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a good indicator to investigate further the entry in created config file and who
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created it to verify if it is a false positive.
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data_source:
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- Sysmon Event ID 11
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search:
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selection1:
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TargetFilename:
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- '*/etc/at.allow'
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- '*/etc/at.deny'
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condition: selection1
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how_to_implement: To successfully implement this search, you need to be ingesting
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logs with the file name, file path, and process_guid executions from your endpoints
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into the Endpoint datamodel. If you are using Sysmon, you can use the Add-on for
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Linux Sysmon from Splunkbase.
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known_false_positives: Administrator or network operator can create this file for
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automation purposes. Please update the filter macros to remove false positives.
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references:
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- https://linuxize.com/post/at-command-in-linux/
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tags:
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analytic_story:
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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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asset_type: Endpoint
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confidence: 50
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impact: 50
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message: A file $file_name$ is created in $file_path$ on $dest$
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mitre_attack_id:
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- T1053.003
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- T1053
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observable:
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- name: dest
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type: Hostname
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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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risk_score: 25
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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/at_execution/sysmon_linux.log
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source: Syslog:Linux-Sysmon/Operational
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sourcetype: sysmon:linux
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