SUSP_ZIP_ISO_PhishAttachment_Pattern_Jun22_1

YARA detection rule by Florian Roth (Nextron Systems) · NOASSERTION

Detects suspicious small base64 encoded ZIP files (MIME email attachments) with .iso files as content as often used in phishing attacks

rule SUSP_ZIP_ISO_PhishAttachment_Pattern_Jun22_1 {
   meta:
      description = "Detects suspicious small base64 encoded ZIP files (MIME email attachments) with .iso files as content as often used in phishing attacks"
      author = "Florian Roth (Nextron Systems)"
      reference = "Internal Research"
      date = "2022-06-23"
      score = 65
      id = "638541a6-d2d4-513e-978c-9d1b9f5e3b71"
   strings:
      $pkzip_base64_1 = { 0A 55 45 73 44 42 }
      $pkzip_base64_2 = { 0A 55 45 73 44 42 }
      $pkzip_base64_3 = { 0A 55 45 73 48 43 }

      $iso_1 = "Lmlzb1BL"
      $iso_2 = "5pc29QS"
      $iso_3 = "uaXNvUE"
   condition:
      filesize < 2000KB and 1 of ($pk*) and 1 of ($iso*)
}

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

08145b8b-346d-4d11-a491-828cd1fbc0cc

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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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