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mhaag-spl
86 lines
3.1 KiB
YAML
86 lines
3.1 KiB
YAML
name: Detect Regasm with Network Connection
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id: 07921114-6db4-4e2e-ae58-3ea8a52ae93f
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version: 2
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date: '2022-02-18'
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author: Michael Haag, Splunk
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type: TTP
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datamodel: []
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description: The following analytic identifies regasm.exe with a network connection
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to a public IP address, exluding private IP space. This particular technique has
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been used in the wild to bypass application control products. Regasm.exe and Regsvcs.exe
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are signed by Microsoft. By contacting a remote command and control server, the
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adversary will have the ability to escalate privileges and complete the objectives.
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During investigation, identify and retrieve the content being loaded. Review parallel
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processes for additional suspicious behavior. Gather any other file modifications
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and review accordingly. Review the reputation of the remote IP or domain and block
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as needed. regsvcs.exe and regasm.exe are natively found in C:\Windows\Microsoft.NET\Framework\v*\regasm|regsvcs.exe
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and C:\Windows\Microsoft.NET\Framework64\v*\regasm|regsvcs.exe.
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search: '`sysmon` EventID=3 dest_ip!=10.0.0.0/12 dest_ip!=172.16.0.0/12 dest_ip!=192.168.0.0/16
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process_name=regasm.exe | rename Computer as dest | stats count min(_time) as firstTime
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max(_time) as lastTime by dest, user, process_name, src_ip, dest_ip | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `detect_regasm_with_network_connection_filter`'
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how_to_implement: To successfully implement this search, you need to be ingesting
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logs with the process name, parent process, and command-line executions from your
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endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the
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Sysmon TA.
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known_false_positives: Although unlikely, limited instances of regasm.exe with a network
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connection may cause a false positive. Filter based endpoint usage, command line
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arguments, or process lineage.
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references:
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- https://attack.mitre.org/techniques/T1218/009/
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- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.009/T1218.009.md
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- https://lolbas-project.github.io/lolbas/Binaries/Regasm/
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tags:
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analytic_story:
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- Suspicious Regsvcs Regasm Activity
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- Living Off The Land
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asset_type: Endpoint
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cis20:
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- CIS 8
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confidence: 100
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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/T1218.009/atomic_red_team/windows-sysmon.log
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impact: 80
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kill_chain_phases:
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- Actions on Objectives
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message: An instance of $process_name$ contacting a remote destination was identified
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on endpoint $Computer$ by user $user$. This behavior is not normal for $process_name$.
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mitre_attack_id:
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- T1218
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- T1218.009
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nist:
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- PR.PT
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- DE.CM
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observable:
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- name: user
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type: User
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role:
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- Victim
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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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- EventID
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- dest_ip
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- process_name
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- Computer
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- user
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- src_ip
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- dest_host
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- dest_ip
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risk_score: 80
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security_domain: endpoint
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