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SEKOIA_Crime_Sload_Vbs_Downloader_Strings_1

Detects an sLoad downloader based on strings

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

What this rule detects

Detects an sLoad downloader based on strings

Associated malware family: Vbsdownloader.

It defines 3 patterns (1 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

crime-sload-vbs-downloader-strings-1.yarDetection Rule License 1.1
rule SEKOIA_Crime_Sload_Vbs_Downloader_Strings_1 : FILE
{
	meta:
		description = "Detects an sLoad downloader based on strings"
		author = "Sekoia.io"
		id = "77ff0d21-9249-43b2-9a6d-87988a2dec3b"
		date = "2022-08-02"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/crime_sload_vbs_downloader_strings_1.yar#L1-L17"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "06e4fcb6c48078c6c44d779820fc901b0f335b9495097ed28206826a959d0712"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "On Error Resume Next"
		$ = {0A [4] 3D 41 72 72 61 79}
		$ = { 2E 50 61 74 74 65 72 6E 20 3D 20 22 28 [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C }

	condition:
		all of them and filesize < 20KB
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$text"On Error Resume Next"
$hex{0A [4] 3D 41 72 72 61 79}
$hex{ 2E 50 61 74 74 65 72 6E 20 3D 20 22 28 [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C [4-10] 7C }

Condition

all of them and filesize < 20KB

In plain words (Heuristic)

  • The file must be smaller than 20KB (a cheap guard that skips large files).
  • All 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: 77ff0d21-9249-43b2-9a6d-87988a2dec3b

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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