webshell_hunting_php_generic_nano_input

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

php webshell having some kind of input and whatever mechanism to execute it. restricted to small files or would give lots of false positives

rule webshell_hunting_php_generic_nano_input: WEBSHELL HUNT {
  meta:
    description = "php webshell having some kind of input and whatever mechanism to execute it. restricted to small files or would give lots of false positives"
    license     = "https://creativecommons.org/licenses/by-nc/4.0/"
    author      = "Arnim Rupp"
    hash        = "b492336ac5907684c1b922e1c25c113ffc303ffbef645b4e95d36bc50e932033"
    date        = "2021/01/13"
    score       = 40

  strings:
    $fp1 = "echo $_POST['"
    $fp2 = "echo $_POST[\""
    $fp3 = "$http_raw_post_data = file_get_contents('php://input');"
    $fp4 = "highlight_file(basename(urldecode($_GET['target'])));"
    $fp5 = "header( \"HTTP/1.0 $_GET[status] $_GET[text]\" );"
    $fp6 = "<?php echo file_get_contents('php://input'); ?>"
    $fp7 = "sleep((int)$_GET['sleep']);"

  condition:
    filesize < 300 and
    capa_php_old_safe and
    capa_php_input and
    not any of ($fp*)
}

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

09293852-d92b-42f5-9f6a-5b282de7a7a1

Propose edits, view related rules, and engage with the community through comments.

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 ]]

Community Discussion