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SEKOIA_Dropper_Win_Selfau3

Finds SelfAU3 Dropper samples based on specific strings

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

What this rule detects

Finds SelfAU3 Dropper samples based on specific strings

It defines 5 patterns (4 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
dropper-win-selfau3.yarDetection Rule License 1.1
rule SEKOIA_Dropper_Win_Selfau3
{
	meta:
		description = "Finds SelfAU3 Dropper samples based on specific strings"
		author = "Sekoia.io"
		id = "2d005a54-b013-40e9-b88a-30454e4b22af"
		date = "2024-02-12"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/dropper_win_selfau3.yar#L1-L24"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "5f69457127ae6cb84b04f72dd30393dbcf32b4ba26ec6d529eebcc03191cbed3"
		score = 75
		quality = 80
		tags = ""
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$sfx = "!Require Windows" ascii
		$ins01 = ";!@Install@!UTF-8!" ascii
		$set = {53 65 74 45 6e 76 69 72 6f 6e 6d 65 6e 74 3d 22 [1-15] 3d ?? 22}
		$run = "RunProgram=\"hidcon:c" ascii
		$ins02 = ";!@InstallEnd@!" ascii

	condition:
		$sfx at 77 and $set in ( @ins01 .. @ins01 + 500 ) and #set > 5 and $run in ( @set .. @set + 1000 ) and $ins02 in ( @run .. @run + 500 )
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$sfxtext"!Require Windows"ascii
$ins01text";!@Install@!UTF-8!"ascii
$sethex{53 65 74 45 6e 76 69 72 6f 6e 6d 65 6e 74 3d 22 [1-15] 3d ?? 22}
$runtext"RunProgram=\"hidcon:c"ascii
$ins02text";!@InstallEnd@!"ascii

Condition

$sfx at 77 and $set in ( @ins01 .. @ins01 + 500 ) and #set > 5 and $run in ( @set .. @set + 1000 ) and $ins02 in ( @run .. @run + 500 )

In plain words (Heuristic)

  • Pattern $set must occur > 5 times.
  • Pattern $sfx must be found at offset 77.
  • Pattern $set must be found within the range @ins01 .. @ins01 + 500.
  • Pattern $run must be found within the range @set .. @set + 1000.
  • Pattern $ins02 must be found within the range @run .. @run + 500.

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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: 2d005a54-b013-40e9-b88a-30454e4b22af

Metadata

version1.0
classificationTLP:CLEAR

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