Detectionhightest

Suspicious Environment Variable Has Been Registered

Detects the creation of user-specific or system-wide environment variables via the registry. Which contains suspicious commands and strings

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Nasreddine Bencherchali (Nextron Systems)Created Tue Dec 20Updated Thu Aug 17966315ef-c5e1-4767-ba25-fce9c8de3660windows

Log Source

WindowsRegistry Set

ProductWindows← raw: windows

CategoryRegistry Set← raw: registry_set

Detection Logic

detection:
    selection_main:
        TargetObject|contains: '\Environment\'
    selection_details:
        - Details:
              - 'powershell'
              - 'pwsh'
        - Details|contains:
              # Add more suspicious strings in env variables below
              - '\AppData\Local\Temp\'
              - 'C:\Users\Public\'
              # Base64 MZ Header
              - 'TVqQAAMAAAAEAAAA' # MZ..........
              - 'TVpQAAIAAAAEAA8A'
              - 'TVqAAAEAAAAEABAA'
              - 'TVoAAAAAAAAAAAAA'
              - 'TVpTAQEAAAAEAAAA'
              # Base64 Invoke- (UTF-8)
              - 'SW52b2tlL'
              - 'ludm9rZS'
              - 'JbnZva2Ut'
              # Base64 Invoke- (UTF-16LE)
              - 'SQBuAHYAbwBrAGUALQ'
              - 'kAbgB2AG8AawBlAC0A'
              - 'JAG4AdgBvAGsAZQAtA'
        - Details|startswith:  # https://gist.github.com/Neo23x0/6af876ee72b51676c82a2db8d2cd3639
              - 'SUVY'
              - 'SQBFAF'
              - 'SQBuAH'
              - 'cwBhA'
              - 'aWV4'
              - 'aQBlA'
              - 'R2V0'
              - 'dmFy'
              - 'dgBhA'
              - 'dXNpbm'
              - 'H4sIA'
              - 'Y21k'
              - 'cABhAH'
              - 'Qzpc'
              - 'Yzpc'
    condition: all of selection_*