Uncommon Outbound Kerberos Connection

Hunt Hypothesis

Detects uncommon outbound network activity via Kerberos default port indicating possible lateral movement or first stage PrivEsc via delegation.

Detection Rule

Sigma (Original)

title: Uncommon Outbound Kerberos Connection
id: e54979bd-c5f9-4d6c-967b-a04b19ac4c74
related:
    - id: eca91c7c-9214-47b9-b4c5-cb1d7e4f2350
      type: similar
status: test
description: |
    Detects uncommon outbound network activity via Kerberos default port indicating possible lateral movement or first stage PrivEsc via delegation.
references:
    - https://github.com/GhostPack/Rubeus
author: Ilyas Ochkov, oscd.community
date: 2019-10-24
modified: 2024-03-15
tags:
    - attack.credential-access
    - attack.t1558
    - attack.lateral-movement
    - attack.t1550.003
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        DestinationPort: 88
        Initiated: 'true'
    filter_main_lsass:
        Image: 'C:\Windows\System32\lsass.exe'
    filter_optional_chrome:
        Image:
            - 'C:\Program Files (x86)\Google\Chrome\Application\chrome.exe'
            - 'C:\Program Files\Google\Chrome\Application\chrome.exe'
    filter_optional_firefox:
        Image:
            - 'C:\Program Files (x86)\Mozilla Firefox\firefox.exe'
            - 'C:\Program Files\Mozilla Firefox\firefox.exe'
    filter_optional_tomcat:
        Image|endswith: '\tomcat\bin\tomcat8.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Web Browsers and third party application might generate similar activity. An initial baseline is required.
level: medium

KQL (Azure Sentinel)

imNetworkSession
| where (DstPortNumber == 88 and NetworkDirection =~ "true") and (not((SrcProcessName =~ "C:\\Windows\\System32\\lsass.exe" or DstProcessName =~ "C:\\Windows\\System32\\lsass.exe"))) and (not((((SrcProcessName in~ ("C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe", "C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe")) or (DstProcessName in~ ("C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe", "C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe"))) or ((SrcProcessName in~ ("C:\\Program Files (x86)\\Mozilla Firefox\\firefox.exe", "C:\\Program Files\\Mozilla Firefox\\firefox.exe")) or (DstProcessName in~ ("C:\\Program Files (x86)\\Mozilla Firefox\\firefox.exe", "C:\\Program Files\\Mozilla Firefox\\firefox.exe"))) or (SrcProcessName endswith "\\tomcat\\bin\\tomcat8.exe" or DstProcessName endswith "\\tomcat\\bin\\tomcat8.exe"))))

Required Data Sources

False Positive Guidance

• Web Browsers and third party application might generate similar activity. An initial baseline is required.

MITRE ATT&CK Context

• Tactic: Credential Access
• Tactic: Lateral Movement
• Technique: T1558 — T1558
• Technique: T1550.003 — T1550.003

References

• https://github.com/GhostPack/Rubeus
• SigmaHQ Rule