YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_WEBSHELL_ASPX_Mar21_1

Detects ASPX Web Shells

WebshellSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compila con YARA-X

Autor: Florian Roth (Nextron Systems)
Fecha: 2021-03-12
Modificada: 2025-11-03
Puntuación / Calidad: 75 / 85

Qué detecta esta regla

Detects ASPX Web Shells

Define 3 patrones (3 de texto, 0 hex, 0 regex).

Resumen generado a partir de los metadatos y la condición de la regla.

Código de la regla

Descargar .yar

webshell-aspx-mar21-1.yarDetection Rule License 1.1

rule SIGNATURE_BASE_WEBSHELL_ASPX_Mar21_1 : FILE
{
	meta:
		description = "Detects ASPX Web Shells"
		author = "Florian Roth (Nextron Systems)"
		id = "52884135-6b86-5e3e-a866-36a812d5a9af"
		date = "2021-03-12"
		modified = "2025-11-03"
		reference = "Internal Research"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/thor-webshells.yar#L9933-L9959"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "10b6e82125a2ddf3cc31a238e0d0c71a64f902e0d77171766713affede03174d"
		hash = "170bee832df176aac0a3c6c7d5aa3fee413b4572030a24c994a97e70f6648ffc"
		hash = "31c4d1fc81c052e269866deff324dffb215e7d481a47a2b6357a572a3e685d90"
		hash = "41b5c26ac194439612b68e9ec6a638eceaf00842c347ffa551eb009ef6c015a3"
		hash = "4b645bc773acde2b3cc204e77ac27c3f6991046c3b75f42d12bc90ec29cff9e3"
		hash = "602bb701b78895d4de32f5e78f3c511e5298ba244b29641b11a7c1c483789859"
		hash = "7ac47a17c511e25c06a53a1c7a5fbbf05f41f047a4a40b71afa81ce7b59f4b03"
		hash = "9a5097d0e8dc29a2814adac070c80fd4b149b33e56aaaf9235af9e87b0501d91"
		hash = "9efb5932c0753e45504fc9e8444209b92c2bdf22e63b1c1a44e2d52cb62b4548"
		hash = "d40b16307d6434c3281374c0e1bbc0f6db388883e7f6266c3c81de0694266882"
		logic_hash = "0c20163871bf424c0b594c4b75d35e782df03761552f792474761c603ddb8478"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$s1 = ".StartInfo.FileName = 'cmd.exe';" ascii
		$s2 = "<xsl:template match=\"\"/root\"\">" ascii fullword
		$s3 = "<?xml version=\"\"1.0\"\"?><root>test</root>\";" ascii fullword

	condition:
		uint16( 0 ) == 0x253c and filesize < 6KB and all of them
}

Cadenas (3 patrones)

Identificador	Tipo	Valor	Modificadores
$s1	texto	".StartInfo.FileName = 'cmd.exe';"	ascii
$s2	texto	"<xsl:template match=\"\"/root\"\">"	ascii fullword
$s3	texto	"<?xml version=\"\"1.0\"\"?><root>test</root>\";"	ascii fullword

Condición

uint16( 0 ) == 0x253c and filesize < 6KB and all of them

En palabras sencillas (Heurística)

El archivo debe ocupar menos de 6KB (un límite barato que descarta archivos grandes).
Deben coincidir todos los patrones de la regla.

Prueba esta regla en tu navegador

Arrastra un archivo para escanearlo con esta regla usando YARA-X compilado a WebAssembly. No se sube nada.

Arrastra un archivo aquí o haz clic para elegirSe escanea en local con YARA-X. Archivos de hasta 200 MB.

Abrir en el editor

Hashes de muestras

Hashes de las muestras que el autor lista en los metadatos de la regla (búscalos en tu plataforma de threat intelligence).

10b6e82125a2ddf3cc31a238e0d0c71a64f902e0d77171766713affede03174d
170bee832df176aac0a3c6c7d5aa3fee413b4572030a24c994a97e70f6648ffc
31c4d1fc81c052e269866deff324dffb215e7d481a47a2b6357a572a3e685d90
41b5c26ac194439612b68e9ec6a638eceaf00842c347ffa551eb009ef6c015a3
4b645bc773acde2b3cc204e77ac27c3f6991046c3b75f42d12bc90ec29cff9e3
602bb701b78895d4de32f5e78f3c511e5298ba244b29641b11a7c1c483789859
7ac47a17c511e25c06a53a1c7a5fbbf05f41f047a4a40b71afa81ce7b59f4b03
9a5097d0e8dc29a2814adac070c80fd4b149b33e56aaaf9235af9e87b0501d91
9efb5932c0753e45504fc9e8444209b92c2bdf22e63b1c1a44e2d52cb62b4548
d40b16307d6434c3281374c0e1bbc0f6db388883e7f6266c3c81de0694266882

Licencia y atribución

Autor: Florian Roth (Nextron Systems)

Repositorio de origen: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licencia: Detection Rule License 1.1 (licencia del repositorio)

Regla original

Obtenida a través de YARA Forge 20260927, que añade a los nombres el prefijo de la fuente y campos meta normalizados.

Id de la regla: 52884135-6b86-5e3e-a866-36a812d5a9af

Etiquetas:FILE

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