Renamed MegaSync Execution

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Sittikorn S
Source: github.com/SigmaHQ/sigma

Detects the execution of a renamed MegaSync.exe as seen used by ransomware families like Nefilim, Sodinokibi, Pysa, and Conti.

Known false positives

Software that illegally integrates MegaSync in a renamed form
Administrators that have renamed MegaSync

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution

Telemetry coverage

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

Rule body

title: Renamed MegaSync Execution
id: 643bdcac-8b82-49f4-9fd9-25a90b929f3b
status: test
description: Detects the execution of a renamed MegaSync.exe as seen used by ransomware families like Nefilim, Sodinokibi, Pysa, and Conti.
references:
    - https://redcanary.com/blog/rclone-mega-extortion/
author: Sittikorn S
date: 2021-06-22
modified: 2023-02-03
tags:
    - attack.stealth
    - attack.t1218
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        OriginalFileName: 'megasync.exe'
    filter:
        Image|endswith: '\megasync.exe'
    condition: selection and not filter
falsepositives:
    - Software that illegally integrates MegaSync in a renamed form
    - Administrators that have renamed MegaSync
level: high

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    OriginalFileName: 'megasync.exe'

Stage 2: `not filter`

filter:
    Image|endswith: '\megasync.exe'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Image`	ends_with	`\megasync.exe`	`excludes:Image` `field:"Image" value:"\megasync.exe"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`OriginalFileName`	eq	`megasync.exe`	`field:"OriginalFileName" kind:eq value:"megasync.exe"`