webshell_hunting_php_generic_nano_payload_or_callback

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

Suspicious: PHP webshell having some method to execute code, no check where it comes from. Restricted to small files or would give lots of false positives

rule webshell_hunting_php_generic_nano_payload_or_callback: WEBSHELL HUNT {
  meta:
    description = "Suspicious: PHP webshell having some method to execute code, no check where it comes from. Restricted to small files or would give lots of false positives"
    license     = "https://creativecommons.org/licenses/by-nc/4.0/"
    author      = "Arnim Rupp"
    date        = "2021/01/14"
    score       = 40
    hash        = "29c80a36f0919c39fb0de4732c506da5eee89783"
    hash        = "76e3491998b76f83b570a4bb66e65dd0de629e9a"

  strings:
    $fp1 = "__DIR__" wide ascii

  condition:
    filesize < 500 and
    capa_php_old_safe and
    (
      (capa_php_payload_evals or capa_php_payload_execs) or
      capa_php_callback
    ) and
    not any of ($fp*)
}

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

1f3da5fc-d167-4379-a46e-85bc457b5a8b

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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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