Publisher 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 ".pub" extension in suspicious or uncommon locations. This could be a sign of attackers abusing Publisher documents

Known false positives

Legitimate usage of ".pub" 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: Publisher Attachment File Dropped In Suspicious Location
id: 3d2a2d59-929c-4b78-8c1a-145dfe9e07b1
status: test
description: Detects creation of files with the ".pub" extension in suspicious or uncommon locations. This could be a sign of attackers abusing Publisher documents
references:
    - https://twitter.com/EmericNasi/status/1623224526220804098
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-08
tags:
    - attack.stealth
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|contains:
            - '\AppData\Local\Temp\'
            - '\Users\Public\'
            - '\Windows\Temp\'
            - 'C:\Temp\'
        TargetFilename|endswith: '.pub'
    condition: selection
falsepositives:
    - Legitimate usage of ".pub" files from those locations
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

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

Indicators

These rows show field, operator, and value matches.

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