Sigma rule: ISO or Image Mount Indicator in Recent Files

Rule

Title

ISO or Image Mount Indicator in Recent Files

Status

test

Level

medium

Author

Florian Roth (Nextron Systems)

Date

2022-02-11

File

rules/windows/file/file_event/file_event_win_iso_file_recent.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product

windows

category

file_event

Detection

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

False positives (as the rule lists them)

• Cases in which a user mounts an image file for legitimate reasons

Tags

• attack.initial-access
• attack.t1566.001

MITRE ATT&CK ids this rule names

• T1566.001

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/

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/file/file_event/file_event_win_iso_file_recent.yml