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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Emotet_BKA_Cleanup_Apr21

No description has been set in the source file - Signature Base

MalwareEmotetSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
press inquiries <info@bka.de>, technical contact <info@mha.bka.de>
Date
2021-03-23
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

No description has been set in the source file - Signature Base

Associated malware family: Emotet.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

mal-emotet-bka-cleanup-apr21.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Emotet_BKA_Cleanup_Apr21 : FILE
{
	meta:
		description = "No description has been set in the source file - Signature Base"
		author = "press inquiries <info@bka.de>, technical contact <info@mha.bka.de>"
		id = "10d93918-8a5e-54a3-81c6-f6ff68562e13"
		date = "2021-03-23"
		modified = "2023-12-05"
		reference = "https://www.bka.de/DE/IhreSicherheit/RichtigesVerhalten/StraftatenImInternet/FAQ/FAQ_node.html"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/crime_emotet.yar#L54-L70"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "533adaed96d015ea2dcd54d5aaf9e71b5b70430ed5733a98618925cf978a6515"
		score = 75
		quality = 85
		tags = "FILE"
		descripton = "This rule targets a modified emotet binary deployed by the Bundeskriminalamt on the 26th of January 2021."
		note = "The binary will replace the original emotet by copying it to a quarantine. It also contains a routine to perform a self-deinstallation on the 25th of April 2021. The three-month timeframe between rollout and self-deinstallation was chosen primarily for evidence purposes as well as to allow remediation."
		sharing = "TLP:WHITE"

	strings:
		$key = { c3 da da 19 63 45 2c 86 77 3b e9 fd 24 64 fb b8 07 fe 12 d0 2a 48 13 38 48 68 e8 ae 91 3c ed 82 }

	condition:
		filesize > 300KB and filesize < 700KB and uint16( 0 ) == 0x5A4D and $key
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$keyhex{ c3 da da 19 63 45 2c 86 77 3b e9 fd 24 64 fb b8 07 fe 12 d0 2a 48 13 38 48 68 e8 ae 91 3c ed 82 }

Condition

filesize > 300KB and filesize < 700KB and uint16( 0 ) == 0x5A4D and $key

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 700KB (a cheap guard that skips large files).
  • The file must be larger than 300KB.
  • Pattern $key must be present.

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References

Licence & attribution

Author: press inquiries <info@bka.de>, technical contact <info@mha.bka.de>

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: 10d93918-8a5e-54a3-81c6-f6ff68562e13

Metadata

descriptonThis rule targets a modified emotet binary deployed by the Bundeskriminalamt on the 26th of January 2021.
noteThe binary will replace the original emotet by copying it to a quarantine. It also contains a routine to perform a self-deinstallation on the 25th of April 2021. The three-month timeframe between rollout and self-deinstallation was chosen primarily for evidence purposes as well as to allow remediation.
sharingTLP:WHITE

Tags:FILE

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