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Detection rules › Sigma

Suspicious Msbuild Execution By Uncommon Parent Process

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects suspicious execution of 'Msbuild.exe' by a uncommon parent process

MITRE ATT&CK coverage

TacticTechniques
StealthNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Suspicious Msbuild Execution By Uncommon Parent Process
id: 33be4333-2c6b-44f4-ae28-102cdbde0a31
status: test
description: Detects suspicious execution of 'Msbuild.exe' by a uncommon parent process
references:
    - https://app.any.run/tasks/abdf586e-df0c-4d39-89a7-06bf24913401/
    - https://www.echotrail.io/insights/search/msbuild.exe
author: frack113
date: 2022-11-17
tags:
    - attack.stealth
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - Image|endswith: '\MSBuild.exe'
        - OriginalFileName: 'MSBuild.exe'
    filter_parent:
        ParentImage|endswith:
            - '\devenv.exe'
            - '\cmd.exe'
            - '\msbuild.exe'
            - '\python.exe'
            - '\explorer.exe'
            - '\nuget.exe'
    condition: selection and not filter_parent
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection and not filter_parent

Stage 1: selection

selection:
    - Image|endswith: '\MSBuild.exe'
    - OriginalFileName: 'MSBuild.exe'

Stage 2: not filter_parent

filter_parent:
    ParentImage|endswith:
        - '\devenv.exe'
        - '\cmd.exe'
        - '\msbuild.exe'
        - '\python.exe'
        - '\explorer.exe'
        - '\nuget.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
ParentImageends_with\cmd.exe
ParentImageends_with\devenv.exe
ParentImageends_with\explorer.exe
ParentImageends_with\msbuild.exe
ParentImageends_with\nuget.exe
ParentImageends_with\python.exe

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Imageends_with
  • \MSBuild.exe corpus 10 (sigma 10)
OriginalFileNameeq
  • MSBuild.exe corpus 11 (elastic 6, splunk 4, sigma 1)