OneNote Attachment File Dropped In Suspicious Location

Status: test
Severity: medium
Log source: category file_event, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects creation of files with the ".one"/".onepkg" extension in suspicious or uncommon locations. This could be a sign of attackers abusing OneNote attachments

Known false positives

Legitimate usage of ".one" or ".onepkg" files from those locations

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: OneNote Attachment File Dropped In Suspicious Location
id: 7fd164ba-126a-4d9c-9392-0d4f7c243df0
status: test
description: Detects creation of files with the ".one"/".onepkg" extension in suspicious or uncommon locations. This could be a sign of attackers abusing OneNote attachments
references:
    - https://www.bleepingcomputer.com/news/security/hackers-now-use-microsoft-onenote-attachments-to-spread-malware/
    - https://blog.osarmor.com/319/onenote-attachment-delivers-asyncrat-malware/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-22
modified: 2023-09-19
tags:
    - attack.stealth
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|contains:
            # Note: add more common locations for drops such as download folders and the like. Or baseline legitimate locations and alert on everything else
            - '\AppData\Local\Temp\'
            - '\Users\Public\'
            - '\Windows\Temp\'
            - ':\Temp\'
        TargetFilename|endswith:
            - '.one'
            - '.onepkg'
    filter_main_onenote:
        Image|contains: ':\Program Files\Microsoft Office\'
        Image|endswith: '\ONENOTE.EXE'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Legitimate usage of ".one" or ".onepkg" files from those locations
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_*

Stage 1: `selection`

selection:
    TargetFilename|contains:
        - '\AppData\Local\Temp\'
        - '\Users\Public\'
        - '\Windows\Temp\'
        - ':\Temp\'
    TargetFilename|endswith:
        - '.one'
        - '.onepkg'

Stage 2: `not filter_main_onenote`

filter_main_onenote:
    Image|contains: ':\Program Files\Microsoft Office\'
    Image|endswith: '\ONENOTE.EXE'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Image`	ends_with	`\ONENOTE.EXE`	`excludes:Image` `field:"Image" value:"\ONENOTE.EXE"`
`Image`	match	`:\Program Files\Microsoft Office\`	`excludes:Image` `field:"Image" value:":\Program Files\Microsoft Office\"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetFilename`	ends_with	`.one` `.onepkg`	`field:"TargetFilename" kind:ends_with`
`TargetFilename`	match	`:\Temp\` corpus 5 (sigma 5) `\AppData\Local\Temp\` corpus 8 (sigma 8) `\Users\Public\` corpus 2 (sigma 2) `\Windows\Temp\` corpus 2 (sigma 2)	`field:"TargetFilename" kind:match`