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Detection rules › Sigma

Emotet Loader Execution Via .LNK File

Status
test
Severity
high
Log source
product windows, category process_creation
Author
@kostastsale
Source
github.com/SigmaHQ/sigma

Detects the Emotet Epoch4 loader as reported by @malware_traffic back in 2022. The ".lnk" file was delivered via phishing campaign.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.006 Command and Scripting Interpreter: Python

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: Emotet Loader Execution Via .LNK File
id: 1f32d820-1d5c-43fe-8fe2-feef0c952eb7
status: test
description: |
    Detects the Emotet Epoch4 loader as reported by @malware_traffic back in 2022.
    The ".lnk" file was delivered via phishing campaign.
references:
    - https://web.archive.org/web/20220422215221/https://twitter.com/malware_traffic/status/1517622327000846338
    - https://twitter.com/Cryptolaemus1/status/1517634855940632576
    - https://tria.ge/220422-1pw1pscfdl/
    - https://tria.ge/220422-1nnmyagdf2/
author: '@kostastsale'
date: 2022-04-22
modified: 2024-08-15
tags:
    - attack.execution
    - attack.t1059.006
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\cmd.exe'
            - '\explorer.exe'
            - '\powershell.exe'
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains|all:
            - 'findstr'
            - '.vbs'
            - '.lnk'
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ParentImage|endswith:
        - '\cmd.exe'
        - '\explorer.exe'
        - '\powershell.exe'
    Image|endswith:
        - '\cmd.exe'
        - '\powershell.exe'
    CommandLine|contains|all:
        - 'findstr'
        - '.vbs'
        - '.lnk'

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
CommandLinematch
  • .lnk corpus 3 (sigma 3)
  • .vbs corpus 7 (sigma 7)
  • findstr corpus 8 (sigma 6, splunk 2)
Imageends_with
  • \cmd.exe corpus 130 (sigma 130)
  • \powershell.exe corpus 182 (sigma 182)
ParentImageends_with
  • \cmd.exe corpus 20 (sigma 20)
  • \explorer.exe corpus 13 (sigma 13)
  • \powershell.exe corpus 24 (sigma 24)