MAL_EarthWorm_Socks_Proxy_ID_Generation

YARA detection rule by NCSC · NOASSERTION

Detects EarthWorm - a reverse socks proxy used by the threat group that deployed Pygmy Goat malware on Sophos XG firewall devices. The detection is based on the pool num generation x86 assembly.

rule MAL_EarthWorm_Socks_Proxy_ID_Generation {
   meta:
      description = "Detects EarthWorm - a reverse socks proxy used by the threat group that deployed Pygmy Goat malware on Sophos XG firewall devices. The detection is based on the pool num generation x86 assembly."
      reference = "https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/pygmy-goat/ncsc-mar-pygmy-goat.pdf"
      author = "NCSC"
      date = "2024-10-22"
      score = 75
      hash1 = "71f70d61af00542b2e9ad64abd2dda7e437536ff"
      id = "242777e4-3abb-50d8-8c45-746cc4a8b1f8"
   strings:
      $chartoi = {
         8b 45 ??          c1 e0 07          89 c1          8b 55 ??          8b 45 ??          01 d0          0f b6 00          0f be c0          01 c8          89 45 ??          83 6d ?? 01       }
   condition:
      uint32(0) == 0x464c457f and all of them
}

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

02b4b22f-a468-4c26-a643-a6b1948dd8e7

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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

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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.

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

[[ currentRule.title ]]

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