Sigma rule: Suspicious Encoded And Obfuscated Reflection Assembly Load Function Call

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-dba3c233d147, updated 2023-04-06T00:00:00.000Z.

Rule

Title
Suspicious Encoded And Obfuscated Reflection Assembly Load Function Call
Status
test
Level
high
Author
pH-T (Nextron Systems)
Date
2022-03-01
Modified
2023-04-06
File
rules/windows/process_creation/proc_creation_win_powershell_base64_reflection_assembly_load_obfusc.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious base64 encoded and obfuscated "LOAD" keyword used in .NET "reflection.assembly"

Log source

product
windows
category
process_creation

Detection

selection:
    CommandLine|contains:
        # ::("L"+"oad")
        - 'OgA6ACgAIgBMACIAKwAiAG8AYQBkACIAKQ'
        - 'oAOgAoACIATAAiACsAIgBvAGEAZAAiACkA'
        - '6ADoAKAAiAEwAIgArACIAbwBhAGQAIgApA'
        # ::("Lo"+"ad")
        - 'OgA6ACgAIgBMAG8AIgArACIAYQBkACIAKQ'
        - 'oAOgAoACIATABvACIAKwAiAGEAZAAiACkA'
        - '6ADoAKAAiAEwAbwAiACsAIgBhAGQAIgApA'
        # ::("Loa"+"d")
        - 'OgA6ACgAIgBMAG8AYQAiACsAIgBkACIAKQ'
        - 'oAOgAoACIATABvAGEAIgArACIAZAAiACkA'
        - '6ADoAKAAiAEwAbwBhACIAKwAiAGQAIgApA'
        # ::('L'+'oad')
        - 'OgA6ACgAJwBMACcAKwAnAG8AYQBkACcAKQ'
        - 'oAOgAoACcATAAnACsAJwBvAGEAZAAnACkA'
        - '6ADoAKAAnAEwAJwArACcAbwBhAGQAJwApA'
        # ::('Lo'+'ad')
        - 'OgA6ACgAJwBMAG8AJwArACcAYQBkACcAKQ'
        - 'oAOgAoACcATABvACcAKwAnAGEAZAAnACkA'
        - '6ADoAKAAnAEwAbwAnACsAJwBhAGQAJwApA'
        # ::('Loa'+'d')
        - 'OgA6ACgAJwBMAG8AYQAnACsAJwBkACcAKQ'
        - 'oAOgAoACcATABvAGEAJwArACcAZAAnACkA'
        - '6ADoAKAAnAEwAbwBhACcAKwAnAGQAJwApA'
condition: selection

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.execution
  • attack.stealth
  • attack.t1059.001
  • attack.t1027

MITRE ATT&CK ids this rule names

Related rules

References

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/process_creation/proc_creation_win_powershell_base64_reflection_assembly_load_obfusc.yml

Sources and licences

  • SigmaHQ

    "Suspicious Encoded And Obfuscated Reflection Assembly Load Function Call" by pH-T (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_base64_reflection_assembly_load_obfusc.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious Encoded And Obfuscated Reflection Assembly Load Function Call",
entity page, dataset version ref-dba3c233d147, updated 2023-04-06T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/9c0295ce-d60d-40bd-bd74-84673b7592b1 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 9c0295ce-d60d-40bd-bd74-84673b7592b1, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.