Sigma rule: Suspicious Obfuscated PowerShell Code

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9d3e9e8dbb4f, updated 2023-02-14T00:00:00.000Z.

Rule

Title
Suspicious Obfuscated PowerShell Code
Status
test
Level
high
Author
Florian Roth (Nextron Systems)
Date
2022-07-11
Modified
2023-02-14
File
rules/windows/process_creation/proc_creation_win_powershell_base64_encoded_obfusc.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious UTF16 and base64 encoded and often obfuscated PowerShell code often used in command lines

Log source

product
windows
category
process_creation

Detection

selection:
    CommandLine|contains:
        #  -bxor 0x
        - 'IAAtAGIAeABvAHIAIAAwAHgA'
        - 'AALQBiAHgAbwByACAAMAB4A'
        - 'gAC0AYgB4AG8AcgAgADAAeA'
        # .Invoke() |
        - 'AC4ASQBuAHYAbwBrAGUAKAApACAAfAAg'
        - 'AuAEkAbgB2AG8AawBlACgAKQAgAHwAI'
        - 'ALgBJAG4AdgBvAGsAZQAoACkAIAB8AC'
        # {1}{0}" -f
        # {0}{3}" -f
        # {2}{0}" -f
        - 'AHsAMQB9AHsAMAB9ACIAIAAtAGYAI'
        - 'B7ADEAfQB7ADAAfQAiACAALQBmAC'
        - 'AewAxAH0AewAwAH0AIgAgAC0AZgAg'
        - 'AHsAMAB9AHsAMwB9ACIAIAAtAGYAI'
        - 'B7ADAAfQB7ADMAfQAiACAALQBmAC'
        - 'AewAwAH0AewAzAH0AIgAgAC0AZgAg'
        - 'AHsAMgB9AHsAMAB9ACIAIAAtAGYAI'
        - 'B7ADIAfQB7ADAAfQAiACAALQBmAC'
        - 'AewAyAH0AewAwAH0AIgAgAC0AZgAg'
        # {1}{0}' -f
        # {0}{3}' -f
        # {2}{0}' -f
        - 'AHsAMQB9AHsAMAB9ACcAIAAtAGYAI'
        - 'B7ADEAfQB7ADAAfQAnACAALQBmAC'
        - 'AewAxAH0AewAwAH0AJwAgAC0AZgAg'
        - 'AHsAMAB9AHsAMwB9ACcAIAAtAGYAI'
        - 'B7ADAAfQB7ADMAfQAnACAALQBmAC'
        - 'AewAwAH0AewAzAH0AJwAgAC0AZgAg'
        - 'AHsAMgB9AHsAMAB9ACcAIAAtAGYAI'
        - 'B7ADIAfQB7ADAAfQAnACAALQBmAC'
        - 'AewAyAH0AewAwAH0AJwAgAC0AZgAg'
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.stealth

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_encoded_obfusc.yml

Sources and licences

  • SigmaHQ

    "Suspicious Obfuscated PowerShell Code" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_base64_encoded_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 Obfuscated PowerShell Code",
entity page, dataset version ref-9d3e9e8dbb4f, updated 2023-02-14T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/8d01b53f-456f-48ee-90f6-bc28e67d4e35 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 8d01b53f-456f-48ee-90f6-bc28e67d4e35, 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.