Potential Rcdll.DLL Sideloading

Hunt Hypothesis

Detects potential DLL sideloading of rcdll.dll

Detection Rule

Sigma (Original)

title: Potential Rcdll.DLL Sideloading
id: 6e78b74f-c762-4800-82ad-f66787f10c8a
status: test
description: Detects potential DLL sideloading of rcdll.dll
references:
    - https://www.trendmicro.com/en_us/research/23/c/iron-tiger-sysupdate-adds-linux-targeting.html
author: X__Junior (Nextron Systems)
date: 2023-03-13
modified: 2023-03-15
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    category: image_load
    product: windows
detection:
    selection:
        ImageLoaded|endswith: '\rcdll.dll'
    filter:
        ImageLoaded|startswith:
            - 'C:\Program Files (x86)\Microsoft Visual Studio\'
            - 'C:\Program Files (x86)\Windows Kits\'
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

KQL (Microsoft 365 Defender)

DeviceImageLoadEvents
| where FolderPath endswith "\\rcdll.dll" and (not((FolderPath startswith "C:\\Program Files (x86)\\Microsoft Visual Studio\\" or FolderPath startswith "C:\\Program Files (x86)\\Windows Kits\\")))

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Persistence
• Tactic: Privilege Escalation
• Tactic: Execution
• Technique: T1574.001 — T1574.001

References

• https://www.trendmicro.com/en_us/research/23/c/iron-tiger-sysupdate-adds-linux-targeting.html
• SigmaHQ Rule