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Detection rules › Sigma

Suspicious GrpConv Execution

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

Detects the suspicious execution of a utility to convert Windows 3.x .grp files or for persistence purposes by malicious software or actors

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1547 Boot or Logon Autostart Execution
Privilege EscalationT1547 Boot or Logon Autostart Execution

Event coverage

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

Rule body yaml

title: Suspicious GrpConv Execution
id: f14e169e-9978-4c69-acb3-1cff8200bc36
status: test
description: Detects the suspicious execution of a utility to convert Windows 3.x .grp files or for persistence purposes by malicious software or actors
references:
    - https://twitter.com/0gtweet/status/1526833181831200770
author: Florian Roth (Nextron Systems)
date: 2022-05-19
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1547
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains:
            - 'grpconv.exe -o'
            - 'grpconv -o'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    CommandLine|contains:
        - 'grpconv.exe -o'
        - 'grpconv -o'

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
  • grpconv -o
  • grpconv.exe -o