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EMBEERESEARCH_Win_Stealc_Bytecodes_Oct_2023

Bytecodes present in Stealc decoding routine

MalwareStealcEmbee ResearchDetection Rule License 1.1Compiles with YARA-X
Author
Matthew @ Embee_Research
Date
2023-08-27
Modified
2023-10-09
Score / Quality
75 / 75

What this rule detects

Bytecodes present in Stealc decoding routine

Associated malware family: Stealc.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
win-stealc-bytecodes-oct-2023.yarDetection Rule License 1.1
rule EMBEERESEARCH_Win_Stealc_Bytecodes_Oct_2023
{
	meta:
		description = "Bytecodes present in Stealc decoding routine"
		author = "Matthew @ Embee_Research"
		id = "ecac28a0-cd77-5e6a-8af2-59ea62e733bf"
		date = "2023-08-27"
		modified = "2023-10-09"
		reference = "https://github.com/embee-research/Yara-detection-rules/"
		source_url = "https://github.com/embee-research/Yara-detection-rules//blob/ac56d6f6fd2a30c8cb6e5c0455d6519210a8b0f4/Rules/win_stealc_bytecodes_oct_2023.yar#L2-L21"
		license_url = "N/A"
		hash = "74ff68245745b9d4cec9ef3c539d8da15295bdc70caa6fdb0632acdd9be4130a"
		hash = "9f44a4cbc30e7a05d7eb00b531a9b3a4ada5d49ecf585b48892643a189358526"
		logic_hash = "d50f57e32a7f513d92625549fcd139b7fa1e478879283fd61426fcd19d03d296"
		score = 75
		quality = 75
		tags = ""

	strings:
		$s1 = {8b 4d f0 89 4d f8 8b 45 f8 c1 e0 03 33 d2 b9 06 00 00 00 f7 f1 8b e5 5d c2 04 00}

	condition:
		( all of ( $s* ) )
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$s1hex{8b 4d f0 89 4d f8 8b 45 f8 c1 e0 03 33 d2 b9 06 00 00 00 f7 f1 8b e5 5d c2 04 00}

Condition

( all of ( $s* ) )

In plain words (Heuristic)

  • All patterns in ( $s* ) must match.

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References

Sample hashes

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

  • 74ff68245745b9d4cec9ef3c539d8da15295bdc70caa6fdb0632acdd9be4130a
  • 9f44a4cbc30e7a05d7eb00b531a9b3a4ada5d49ecf585b48892643a189358526

Licence & attribution

Author: Matthew @ Embee_Research

Source repository: Embee Research @ ac56d6f6fd

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: ecac28a0-cd77-5e6a-8af2-59ea62e733bf

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