HackTool - KrbRelay Execution

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the use of KrbRelay, a Kerberos relaying tool

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1558.003` Steal or Forge Kerberos Tickets: Kerberoasting

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: HackTool - KrbRelay Execution
id: e96253b8-6b3b-4f90-9e59-3b24b99cf9b4
status: test
description: Detects the use of KrbRelay, a Kerberos relaying tool
references:
    - https://github.com/cube0x0/KrbRelay
author: Florian Roth (Nextron Systems)
date: 2022-04-27
modified: 2023-02-04
tags:
    - attack.credential-access
    - attack.t1558.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\KrbRelay.exe'
        - OriginalFileName: 'KrbRelay.exe' # In case the file has been renamed after compilation
    selection_cli_1:
        CommandLine|contains|all:
            - ' -spn '
            - ' -clsid '
            - ' -rbcd '
    selection_cli_2:
        CommandLine|contains|all:
            - 'shadowcred'
            - 'clsid'
            - 'spn'
    selection_cli_3:
        CommandLine|contains|all:
            - 'spn '
            - 'session '
            - 'clsid '
    condition: 1 of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\KrbRelay.exe'
    - OriginalFileName: 'KrbRelay.exe'

Stage 2: `selection_cli_1`

selection_cli_1:
    CommandLine|contains|all:
        - ' -spn '
        - ' -clsid '
        - ' -rbcd '

Stage 3: `selection_cli_2`

selection_cli_2:
    CommandLine|contains|all:
        - 'shadowcred'
        - 'clsid'
        - 'spn'

Stage 4: `selection_cli_3`

selection_cli_3:
    CommandLine|contains|all:
        - 'spn '
        - 'session '
        - 'clsid '

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`-clsid` corpus 2 (sigma 2) `-rbcd` `-spn` `clsid` `clsid` `session` `shadowcred` `spn` `spn`	`field:"CommandLine" kind:match`
`Image`	ends_with	`\KrbRelay.exe`	`field:"Image" kind:ends_with value:"\KrbRelay.exe"`
`OriginalFileName`	eq	`KrbRelay.exe`	`field:"OriginalFileName" kind:eq value:"KrbRelay.exe"`

HackTool - KrbRelay Execution

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli_1

Stage 3: selection_cli_2

Stage 4: selection_cli_3

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_1`

Stage 3: `selection_cli_2`

Stage 4: `selection_cli_3`