encoded_frombase64string

rule encoded_frombase64string {
 meta:
    author = "Florian Roth"
    description = "Detects a base64 encoded FromBase64String keyword in a process command line  License: https://github.com/Neo23x0/sigma/blob/master/LICENSE.Detection.Rules.md."
    reference = "https://tdm.socprime.com/tdm/info/bZM3R651aDgG"
    version = "0.01"
    created = "2019/08/24"
    category = "process_creation"
    product = "windows"
    mitre = "t1086, t1140, execution, defense_evasion"

  events:
((re.regex($selection.target.process.command_line, `.*OjpGcm9tQmFzZTY0U3RyaW5n.*`) or re.regex($selection.target.process.command_line, `.*o6RnJvbUJhc2U2NFN0cmluZ.*`) or re.regex($selection.target.process.command_line, `.*6OkZyb21CYXNlNjRTdHJpbm.*`)) and ($selection.metadata.product_event_type = "4688" or $selection.metadata.product_event_type = "1"))

  condition:
    $selection
}