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VOLEXITY_Webshell_Php_Icescorpion

YARA detection rule by threatintel@volexity.com · See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt

Detects the IceScorpion webshell.

rule VOLEXITY_Webshell_Php_Icescorpion: COMMODITY WEBSHELL FILE {
  meta:
    description     = "Detects the IceScorpion webshell."
    author          = "threatintel@volexity.com"
    id              = "dd165d67-375e-5d51-825a-45241345e268"
    date            = "2022-01-17"
    modified        = "2022-07-28"
    reference       = "https://www.codenong.com/cs106064226/"
    source_url      = "https://github.com/volexity/threat-intel/blob/62e031ea574efde68dac7d38dc23438466a5302b/2022/2022-06-15 DriftingCloud - Zero-Day Sophos Firewall Exploitation and an Insidious Breach/indicators/yara.yar#L172-L190"
    license_url     = "https://github.com/volexity/threat-intel/blob/62e031ea574efde68dac7d38dc23438466a5302b/LICENSE.txt"
    logic_hash      = "0c75ec7cbbfdba8ce5f71a83d78caf19366954b84f304c1864e68bbe11a9a2df"
    score           = 75
    quality         = 80
    tags            = "COMMODITY, WEBSHELL, FILE"
    hash1           = "5af4788d1a61009361b37e8db65deecbfea595ef99c3cf920d33d9165b794972"
    license         = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"
    memory_suitable = 0

  strings:
    $s1 = "[$i+1&15];"
    $s2 = "openssl_decrypt"

  condition:
    all of them and filesize < 10KB
}

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

79d22756-9fd1-4ed8-8e2e-c9903c6d041f

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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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