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70 lines
2.8 KiB
YAML
70 lines
2.8 KiB
YAML
name: Excessive number of taskhost processes
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id: f443dac2-c7cf-11eb-ab51-acde48001122
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version: 1
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date: '2021-06-07'
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author: Michael Hart
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type: batch
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datamodel:
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- Endpoint
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description: This detection targets behaviors observed in post exploit kits like Meterpreter
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and Koadic that are run in memory. We have observed that these tools must invoke
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an excessive number of taskhost.exe and taskhostex.exe processes to complete various
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actions (discovery, lateral movement, etc.). It is extremely uncommon in the course
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of normal operations to see so many distinct taskhost and taskhostex processes running
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concurrently in a short time frame.
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search: '| tstats `security_content_summariesonly` values(Processes.process_id) as
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process_ids min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
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WHERE Processes.process_name = "taskhost.exe" OR Processes.process_name = "taskhostex.exe"
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BY Processes.dest Processes.process_name _time span=1h | `drop_dm_object_name(Processes)`
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| eval pid_count=mvcount(process_ids) | eval taskhost_count_=if(process_name ==
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"taskhost.exe", pid_count, 0) | eval taskhostex_count_=if(process_name == "taskhostex.exe",
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pid_count, 0) | stats sum(taskhost_count_) as taskhost_count, sum(taskhostex_count_)
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as taskhostex_count by _time, dest, firstTime, lastTime | where taskhost_count >
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10 and taskhostex_count > 10 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `excessive_number_of_taskhost_processes_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting events
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related to processes on the endpoints that include the name of the process and process
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id into the `Endpoint` datamodel in the `Processes` node.
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known_false_positives: Administrators, administrative actions or certain applications
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may run many instances of taskhost and taskhostex concurrently. Filter as needed.
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references:
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- https://attack.mitre.org/software/S0250/
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tags:
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analytic_story:
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- Meterpreter
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automated_detection_testing: passed
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confidence: 70
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context:
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- Source:Endpoint
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- Stage:Defense Evasion
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059/meterpreter/taskhost_processes/logExcessiveTaskHost.log
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impact: 80
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kill_chain_phases:
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- Exploitation
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message: An excessive amount of $process_name$ was executed on $dest$ indicative
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of suspicious behavior.
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mitre_attack_id:
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- T1033
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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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- name: process_name
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type: Process
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role:
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- Child Process
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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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required_fields:
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- _time
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- Processes.process_id
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- Processes.process_name
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- Processes.dest
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- Processes.user
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risk_score: 56
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security_domain: endpoint
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