name: Linux Ingress Tool Transfer with Curl
id: 8c1de57d-abc1-4b41-a727-a7a8fc5e0857
version: 1
date: '2022-07-29'
author: Michael Haag, Splunk
status: production
type: Anomaly
description: The following analytic identifies curl with the command-line switches
  that are commonly used to download, output, a remote script or binary. MetaSploit
  Framework will combine the -sO switch with | chmod +x to enable a simple one liner
  to download and set the execute bit to run the file immediately. During triage,
  review the remote domain and file being downloaded for legitimacy.
data_source:
- Sysmon Event ID 1
search:
  selection1:
    Image|endswith: curl
  condition: selection1
how_to_implement: To successfully implement this search you need to be ingesting information
  on process that include the name of the process responsible for the changes from
  your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
  confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
  endpoint product.
known_false_positives: False positives will be present. Tune and then change type
  to TTP.
references:
- https://gtfobins.github.io/gtfobins/curl/
- https://curl.se/docs/manpage.html#-I
- https://gtfobins.github.io/gtfobins/curl/
- https://github.com/rapid7/metasploit-framework/search?q=curl
tags:
  analytic_story:
  - Linux Living Off The Land
  - Ingress Tool Transfer
  asset_type: Endpoint
  confidence: 30
  impact: 40
  message: An instance of $process_name$ was identified on endpoint $dest$ by user
    $user$ to download a remote file. Review activity for further details.
  mitre_attack_id:
  - T1105
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 12
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1105/atomic_red_team/curl-linux-sysmon.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon_linux
    update_timestamp: true