webshell_asp_generic_tiny_ren

YARA detection rule by Arnim Rupp · https://creativecommons.org/licenses/by-nc/4.0/

Generic tiny ASP webshell which uses any eval/exec function indirectly on user input or writes a file

rule webshell_asp_generic_tiny_ren: WEBSHELL PROD {
  meta:
    description = "Generic tiny ASP webshell which uses any eval/exec function indirectly on user input or writes a file"
    license     = "https://creativecommons.org/licenses/by-nc/4.0/"
    author      = "Arnim Rupp"
    date        = "2021/01/07"
    hash        = "990e3f129b8ba409a819705276f8fa845b95dad0"
    hash        = "52ce724580e533da983856c4ebe634336f5fd13a"

  strings:
    $fp1 = "net.rim.application.ipproxyservice.AdminCommand.execute"

  condition:
    capa_asp and
    capa_asp_input and
    not 1 of ($fp*) and
    not capa_bin_files and
    (
      filesize < 700 and
      (
        capa_asp_payload or
        capa_asp_write_file
      )
    )
}

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

09475107-478a-44ea-a396-768080965cac

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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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