Skip to content
yararules.org
Menu

YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_DOC_Zloader_Oct20_1

Detects weaponized ZLoader documents

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth (Nextron Systems)
Date
2020-10-10
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects weaponized ZLoader documents

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-doc-zloader-oct20-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_DOC_Zloader_Oct20_1 : FILE
{
	meta:
		description = "Detects weaponized ZLoader documents"
		author = "Florian Roth (Nextron Systems)"
		id = "34145746-9733-5dd9-9dcf-99e3a3ceee4f"
		date = "2020-10-10"
		modified = "2023-12-05"
		reference = "https://twitter.com/JohnLaTwC/status/1314602421977452544"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/crime_zloader_maldocs.yar#L2-L22"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "668ca7ede54664360b0a44d5e19e76beb92c19659a8dec0e7085d05528df42b5"
		hash = "a2ffabbb1b5a124f462a51fee41221081345ec084d768ffe1b1ef72d555eb0a0"
		hash = "d268af19db475893a3d19f76be30bb063ab2ca188d1b5a70e51d260105b201da"
		logic_hash = "6f546a860361d3caff99c282465dbbd1880460c7491a1b5ad065c1b5d91e5d49"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$sc1 = { 78 4E FC 04 AB 6B 17 E2 33 E3 49 62 50 69 BB 60
               31 00 1E 00 02 4B BA E2 D8 E3 92 22 1E 69 96 20
               98 }
		$sc2 = { 6B 9E E2 36 E3 69 62 72 69 3A 60 55 6E }
		$sc3 = { 3E 69 76 60 59 6E 34 FB 87 6B 75 }

	condition:
		uint16( 0 ) == 0xcfd0 and filesize < 40KB and filesize > 30KB and all of them
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$sc1hex{ 78 4E FC 04 AB 6B 17 E2 33 E3 49 62 50 69 BB 60 31 00 1E 00 02 4B BA E2 D8 E3 92 22 1E 69 96 20 98 }
$sc2hex{ 6B 9E E2 36 E3 69 62 72 69 3A 60 55 6E }
$sc3hex{ 3E 69 76 60 59 6E 34 FB 87 6B 75 }

Condition

uint16( 0 ) == 0xcfd0 and filesize < 40KB and filesize > 30KB and all of them

In plain words (Heuristic)

  • The file must be smaller than 40KB (a cheap guard that skips large files).
  • The file must be larger than 30KB.
  • All patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

  • 668ca7ede54664360b0a44d5e19e76beb92c19659a8dec0e7085d05528df42b5
  • a2ffabbb1b5a124f462a51fee41221081345ec084d768ffe1b1ef72d555eb0a0
  • d268af19db475893a3d19f76be30bb063ab2ca188d1b5a70e51d260105b201da

Licence & attribution

Author: Florian Roth (Nextron Systems)

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

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: 34145746-9733-5dd9-9dcf-99e3a3ceee4f

Tags:FILE

Related rules