sigmamediumHunting

ISO or Image Mount Indicator in Recent Files

Detects the creation of recent element file that points to an .ISO, .IMG, .VHD or .VHDX file as often used in phishing attacks. This can be a false positive on server systems but on workstations users should rarely mount .iso or .img files.

MITRE ATT&CK

T1566.001

initial-access

Detection Query

selection:
  TargetFilename|endswith:
    - .iso.lnk
    - .img.lnk
    - .vhd.lnk
    - .vhdx.lnk
  TargetFilename|contains: \Microsoft\Windows\Recent\
condition: selection

Author

Florian Roth (Nextron Systems)

Created

2022-02-11

Data Sources

windowsFile Events

Platforms

windows

References

Tags

attack.initial-accessattack.t1566.001

Raw Content

title: ISO or Image Mount Indicator in Recent Files
id: 4358e5a5-7542-4dcb-b9f3-87667371839b
status: test
description: |
    Detects the creation of recent element file that points to an .ISO, .IMG, .VHD or .VHDX file as often used in phishing attacks.
    This can be a false positive on server systems but on workstations users should rarely mount .iso or .img files.
references:
    - https://www.microsoft.com/security/blog/2021/05/27/new-sophisticated-email-based-attack-from-nobelium/
    - https://www.trendmicro.com/vinfo/us/security/news/cybercrime-and-digital-threats/malicious-spam-campaign-uses-iso-image-files-to-deliver-lokibot-and-nanocore
    - https://blog.emsisoft.com/en/32373/beware-new-wave-of-malware-spreads-via-iso-file-email-attachments/
    - https://insights.sei.cmu.edu/blog/the-dangers-of-vhd-and-vhdx-files/
author: Florian Roth (Nextron Systems)
date: 2022-02-11
tags:
    - attack.initial-access
    - attack.t1566.001
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|endswith:
            - '.iso.lnk'
            - '.img.lnk'
            - '.vhd.lnk'
            - '.vhdx.lnk'
        TargetFilename|contains: '\Microsoft\Windows\Recent\'
    condition: selection
falsepositives:
    - Cases in which a user mounts an image file for legitimate reasons
level: medium