Unknown Process Using The Kerberos Protocol

SPLUNK detection rule by Mauricio Velazco, Splunk · Apache-2.0

The following analytic identifies a non-lsass.exe process making an outbound connection on port 88, which is typically used by the Kerberos authentication protocol. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and network traffic logs. This activity is significant because, under normal circumstances, only the lsass.exe process should interact with the Kerberos Distribution Center. If confirmed malicious, this behavior could indicate an adversary attempting to abuse the Kerberos protocol, potentially leading to unauthorized access or lateral movement within the network.

name: Unknown Process Using The Kerberos Protocol
id: c91a0852-9fbb-11ec-af44-acde48001122
version: 12
creation_date: '2022-03-10'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic identifies a non-lsass.exe process making an outbound connection on port 88, which is typically used by the Kerberos authentication protocol. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and network traffic logs. This activity is significant because, under normal circumstances, only the lsass.exe process should interact with the Kerberos Distribution Center. If confirmed malicious, this behavior could indicate an adversary attempting to abuse the Kerberos protocol, potentially leading to unauthorized access or lateral movement within the network.
data_source:
    - Sysmon EventID 1 AND Sysmon EventID 3
search: |-
    | tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
      WHERE Processes.process_name!=lsass.exe
      BY _time Processes.action Processes.dest
         Processes.original_file_name Processes.parent_process Processes.parent_process_exec
         Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name
         Processes.parent_process_path Processes.process Processes.process_exec
         Processes.process_guid Processes.process_hash Processes.process_id
         Processes.process_integrity_level Processes.process_name Processes.process_path
         Processes.user Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | join  process_id dest [
    | tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic
      WHERE All_Traffic.dest_port = 88
      BY All_Traffic.action All_Traffic.app All_Traffic.bytes
         All_Traffic.bytes_in All_Traffic.bytes_out All_Traffic.dest
         All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc
         All_Traffic.protocol All_Traffic.protocol_version All_Traffic.src
         All_Traffic.src_ip All_Traffic.src_port All_Traffic.transport
         All_Traffic.user All_Traffic.vendor_product All_Traffic.direction
         All_Traffic.process_id
    | `drop_dm_object_name(All_Traffic)`
    | rename src as dest ]
    | table _time dest parent_process_name process_name process_path process process_id dest_port
    | `unknown_process_using_the_kerberos_protocol_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: Custom applications may leverage the Kerberos protocol. Filter as needed.
references:
    - https://stealthbits.com/blog/how-to-detect-overpass-the-hash-attacks/
    - https://www.thehacker.recipes/ad/movement/kerberos/ptk
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: Unknown process $process_name$ using the kerberos protocol detected on host $dest$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Active Directory Kerberos Attacks
    - BlackSuit Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1550
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1550/rubeus/windows-security.log
          source: WinEventLog:Security
          sourcetype: WinEventLog
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1550/rubeus/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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