Mimic_dropper

YARA detection rule by rivitna · GPL-2.0

Mimic ransomware dropper

rule Mimic_dropper {
  meta:
    author      = "rivitna"
    family      = "ransomware.mimic.windows"
    description = "Mimic ransomware dropper"
    severity    = 10
    score       = 100

  strings:
    $h = {
      37 7A 61 2E 65 78 65 20 78 20 2D 79 20 2D 70
      3? 3? 3? 3? [8-12] 3? 3? 3? 3?
      20 45 76 65 72 79 74 68 69 6E 67 36 34 2E 64 6C 6C 22
    }

  condition:
    ((uint16(0) == 0x5A4D) and (uint32(uint32(0x3C)) == 0x00004550)) and
    (filesize > 1500KB) and (filesize < 10000KB) and
    (
      $h in (100000..200000)
    )
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

9bc0759f-dd96-48fa-917e-e96010331fd1

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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