Detection rules › Sigma

Uncommon Outbound Kerberos Connection - Security

Status
test
Severity
medium
Log source
product windows, service security
Author
Ilyas Ochkov, oscd.community
Source
github.com/SigmaHQ/sigma

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

Known false positives

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

MITRE ATT&CK coverage

Telemetry coverage

Rule body

title: Uncommon Outbound Kerberos Connection - Security
id: eca91c7c-9214-47b9-b4c5-cb1d7e4f2350
related:
    - id: e54979bd-c5f9-4d6c-967b-a04b19ac4c74
      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.lateral-movement
    - attack.credential-access
    - attack.t1558.003
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 5156
        DestPort: 88
    filter_main_lsass:
        Application|startswith:
            - '\device\harddiskvolume'
            - 'C:'
        Application|endswith: '\Windows\System32\lsass.exe'
    filter_optional_chrome:
        Application|startswith:
            - '\device\harddiskvolume'
            - 'C:'
        Application|endswith:
            - '\Program Files (x86)\Google\Chrome\Application\chrome.exe'
            - '\Program Files\Google\Chrome\Application\chrome.exe'
    filter_optional_firefox:
        Application|startswith:
            - '\device\harddiskvolume'
            - 'C:'
        Application|endswith:
            - '\Program Files (x86)\Mozilla Firefox\firefox.exe'
            - '\Program Files\Mozilla Firefox\firefox.exe'
    filter_optional_tomcat:
        Application|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

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: selection

selection:
    EventID: 5156
    DestPort: 88

Stage 2: not filter_main_lsass

filter_main_lsass:
    Application|startswith:
        - '\device\harddiskvolume'
        - 'C:'
    Application|endswith: '\Windows\System32\lsass.exe'

Stage 3: not filter_optional_*

filter_optional_chrome:
    Application|startswith:
        - '\device\harddiskvolume'
        - 'C:'
    Application|endswith:
        - '\Program Files (x86)\Google\Chrome\Application\chrome.exe'
        - '\Program Files\Google\Chrome\Application\chrome.exe'
filter_optional_firefox:
    Application|startswith:
        - '\device\harddiskvolume'
        - 'C:'
    Application|endswith:
        - '\Program Files (x86)\Mozilla Firefox\firefox.exe'
        - '\Program Files\Mozilla Firefox\firefox.exe'
filter_optional_tomcat:
    Application|endswith: '\tomcat\bin\tomcat8.exe'

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
Applicationstarts_withC:excludes:Application field:"Application" value:"C:"
Applicationstarts_with\device\harddiskvolumeexcludes:Application field:"Application" value:"\device\harddiskvolume"
Applicationends_with\Windows\System32\lsass.exeexcludes:Application field:"Application" value:"\Windows\System32\lsass.exe"
Applicationends_with\Program Files (x86)\Google\Chrome\Application\chrome.exeexcludes:Application field:"Application" value:"\Program Files (x86)\Google\Chrome\Application\chrome.exe"
Applicationends_with\Program Files\Google\Chrome\Application\chrome.exeexcludes:Application field:"Application" value:"\Program Files\Google\Chrome\Application\chrome.exe"
Applicationends_with\Program Files (x86)\Mozilla Firefox\firefox.exeexcludes:Application field:"Application" value:"\Program Files (x86)\Mozilla Firefox\firefox.exe"
Applicationends_with\Program Files\Mozilla Firefox\firefox.exeexcludes:Application field:"Application" value:"\Program Files\Mozilla Firefox\firefox.exe"
Applicationends_with\tomcat\bin\tomcat8.exeexcludes:Application field:"Application" value:"\tomcat\bin\tomcat8.exe"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
DestPorteq
  • 88 corpus 7 (elastic 4, sigma 2, splunk 1)
field:"DestinationPort" kind:eq value:"88"