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SEKOIA_Hacktool_Earthworm_Strings

Detects Mac/Win/Linux EarthWorm based on strings

Hack toolEarthwormSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2022-02-08
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detects Mac/Win/Linux EarthWorm based on strings

Associated malware family: Earthworm.

Targets: Windows PE, Linux ELF, macOS Mach-O.

It defines 4 patterns (4 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
hacktool-earthworm-strings.yarDetection Rule License 1.1
rule SEKOIA_Hacktool_Earthworm_Strings : FILE
{
	meta:
		description = "Detects Mac/Win/Linux EarthWorm based on strings"
		author = "Sekoia.io"
		id = "6c9b0225-8c41-49f9-9745-245bc7ef942f"
		date = "2022-02-08"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/hacktool_earthworm_strings.yar#L1-L22"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "0460c62fefc3d594ca758a37fbe1716182ffdca2920fedd32a707f7117702176"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "the read url is %s"
		$ = "--> %3d <-- (close)used tunnel %d , unused tunnel %d"
		$ = "ssocksd 0.0.0.0:%d <--[%4d usec]--> socks server"
		$ = "could not create one way tunnel"

	condition:
		( uint32be( 0 ) == 0x7f454c46 or uint16be( 0 ) == 0x4d5a or uint32be( 0 ) == 0xcffaedfe ) and filesize < 100KB and 3 of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$text"the read url is %s"
$text"--> %3d <-- (close)used tunnel %d , unused tunnel %d"
$text"ssocksd 0.0.0.0:%d <--[%4d usec]--> socks server"
$text"could not create one way tunnel"

Condition

( uint32be( 0 ) == 0x7f454c46 or uint16be( 0 ) == 0x4d5a or uint32be( 0 ) == 0xcffaedfe ) and filesize < 100KB and 3 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must start with the ELF header — a Linux/Unix executable.
  • The file must start with a Mach-O / fat binary magic — a macOS executable.
  • The file must be smaller than 100KB (a cheap guard that skips large files).
  • At least 3 patterns in the rule must match.

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References

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 6c9b0225-8c41-49f9-9745-245bc7ef942f

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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