Suspicious DumpMinitool Execution

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

Detects suspicious ways to use the "DumpMinitool.exe" binary

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1036` Masquerading
Credential Access	`T1003.001` OS Credential Dumping: LSASS Memory

Telemetry coverage

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

Rule body

title: Suspicious DumpMinitool Execution
id: eb1c4225-1c23-4241-8dd4-051389fde4ce
status: test
description: Detects suspicious ways to use the "DumpMinitool.exe" binary
references:
    - https://twitter.com/mrd0x/status/1511415432888131586
    - https://twitter.com/mrd0x/status/1511489821247684615
    - https://lolbas-project.github.io/lolbas/OtherMSBinaries/DumpMinitool/
author: Florian Roth (Nextron Systems)
date: 2022-04-06
modified: 2023-04-12
tags:
    - attack.credential-access
    - attack.stealth
    - attack.t1036
    - attack.t1003.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - Image|endswith:
              - '\DumpMinitool.exe'
              - '\DumpMinitool.x86.exe'
              - '\DumpMinitool.arm64.exe'
        - OriginalFileName:
              - 'DumpMinitool.exe'
              - 'DumpMinitool.x86.exe'
              - 'DumpMinitool.arm64.exe'
    filter_folder:
        Image|contains:
            - '\Microsoft Visual Studio\'
            - '\Extensions\'  # https://github.com/microsoft/vstest/blob/b2e2126f1aa7e5753cafe9515563c99ade6a59ce/src/package/nuspec/Microsoft.TestPlatform.Portable.nuspec#L159
    susp_flags:
        CommandLine|contains: '.txt'
    cmd_has_flags:
        CommandLine|contains:
            - ' Full'
            - ' Mini'
            - ' WithHeap'
    filter_cmd_misses_flags:
        CommandLine|contains: '--dumpType'
    condition: selection and ( ( not filter_folder ) or susp_flags or ( cmd_has_flags and not filter_cmd_misses_flags ) )
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection and ( ( not filter_folder ) or susp_flags or ( cmd_has_flags and not filter_cmd_misses_flags ) )

Stage 1: `selection`

selection:
    - Image|endswith:
          - '\DumpMinitool.exe'
          - '\DumpMinitool.x86.exe'
          - '\DumpMinitool.arm64.exe'
    - OriginalFileName:
          - 'DumpMinitool.exe'
          - 'DumpMinitool.x86.exe'
          - 'DumpMinitool.arm64.exe'

Stage 2: `not filter_folder`

filter_folder:
    Image|contains:
        - '\Microsoft Visual Studio\'
        - '\Extensions\'

Stage 3: `susp_flags`

susp_flags:
    CommandLine|contains: '.txt'

Stage 4: `cmd_has_flags`

cmd_has_flags:
    CommandLine|contains:
        - ' Full'
        - ' Mini'
        - ' WithHeap'

Stage 5: `not filter_cmd_misses_flags`

filter_cmd_misses_flags:
    CommandLine|contains: '--dumpType'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Image`	match	`\Extensions\`	`excludes:Image` `field:"Image" value:"\Extensions\"`
`Image`	match	`\Microsoft Visual Studio\`	`excludes:Image` `field:"Image" value:"\Microsoft Visual Studio\"`
`CommandLine`	match	`--dumpType`	`excludes:CommandLine` `field:"CommandLine" value:"--dumpType"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`Full` corpus 3 (sigma 3) `Mini` corpus 2 (sigma 2) `WithHeap` corpus 2 (sigma 2) `.txt` corpus 9 (sigma 9)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\DumpMinitool.arm64.exe` corpus 2 (sigma 2) `\DumpMinitool.exe` corpus 2 (sigma 2) `\DumpMinitool.x86.exe` corpus 2 (sigma 2)	`field:"Image" kind:ends_with`
`OriginalFileName`	eq	`DumpMinitool.arm64.exe` corpus 2 (sigma 2) `DumpMinitool.exe` corpus 4 (sigma 2, elastic 2) `DumpMinitool.x86.exe` corpus 2 (sigma 2)	`field:"OriginalFileName" kind:eq`

Suspicious DumpMinitool Execution

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_folder

Stage 3: susp_flags

Stage 4: cmd_has_flags

Stage 5: not filter_cmd_misses_flags

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_folder`

Stage 3: `susp_flags`

Stage 4: `cmd_has_flags`

Stage 5: `not filter_cmd_misses_flags`