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YARA · ditekSHen detection

DITEKSHEN_INDICATOR_RTF_Embedded_Excel_Sheetmacroenabled

Detects RTF documents embedding an Excel sheet with macros enabled. Observed in exploit followed by dropper behavior

Suspicious / huntingditekSHen detectionBSD 2-Clause LicenseCompiles with YARA-X
Author
ditekSHen
Date
2020-11-06
Modified
2024-09-06
Score / Quality
75 / 75

What this rule detects

Detects RTF documents embedding an Excel sheet with macros enabled. Observed in exploit followed by dropper behavior

It defines 14 patterns (13 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
indicator-rtf-embedded-excel-sheetmacroenabled.yarBSD 2-Clause License
rule DITEKSHEN_INDICATOR_RTF_Embedded_Excel_Sheetmacroenabled : FILE
{
	meta:
		description = "Detects RTF documents embedding an Excel sheet with macros enabled. Observed in exploit followed by dropper behavior"
		author = "ditekSHen"
		id = "342d10b3-61d2-5fcb-8f4f-1fe45049257b"
		date = "2020-11-06"
		modified = "2024-09-06"
		reference = "https://github.com/ditekshen/detection"
		source_url = "https://github.com/ditekshen/detection/blob/e76c93dcdedff04076380ffc60ea54e45b313635/yara/indicator_office.yar#L304-L328"
		license_url = "https://github.com/ditekshen/detection/blob/e76c93dcdedff04076380ffc60ea54e45b313635/LICENSE.txt"
		logic_hash = "cc3b52e549c2697c6e0a2fea365d193311d90d26854bd2fe321aa26c118975a0"
		score = 75
		quality = 75
		tags = "FILE"

	strings:
		$ex1 = "457863656c2e53686565744d6163726f456e61626c65642e" ascii nocase
		$ex2 = "0002083200000000c000000000000046" ascii nocase
		$ex3 = "Excel.SheetMacroEnabled." ascii
		$ole1 = { d0 cf 11 e0 a1 b1 1a e1 }
		$ole2 = "d0cf11e0a1b11ae1" ascii nocase
		$ole3 = "64306366313165306131623131616531" ascii
		$ole4 = "640a300a630a660a310a310a650a300a610a310a620a310a310a610a650a31"
		$obj1 = "\\objhtml" ascii
		$obj2 = "\\objdata" ascii
		$obj3 = "\\objupdate" ascii
		$obj4 = "\\objemb" ascii
		$obj5 = "\\objautlink" ascii
		$obj6 = "\\objlink" ascii
		$obj7 = "\\mmath" ascii

	condition:
		uint32( 0 ) == 0x74725c7b and ( 1 of ( $ex* ) and 1 of ( $ole* ) and 2 of ( $obj* ) )
}

Strings (14 patterns)

IdentifierTypeValueModifiers
$ex1text"457863656c2e53686565744d6163726f456e61626c65642e"ascii nocase
$ex2text"0002083200000000c000000000000046"ascii nocase
$ex3text"Excel.SheetMacroEnabled."ascii
$ole1hex{ d0 cf 11 e0 a1 b1 1a e1 }
$ole2text"d0cf11e0a1b11ae1"ascii nocase
$ole3text"64306366313165306131623131616531"ascii
$ole4text"640a300a630a660a310a310a650a300a610a310a620a310a310a610a650a31"
$obj1text"\\objhtml"ascii
$obj2text"\\objdata"ascii
$obj3text"\\objupdate"ascii
$obj4text"\\objemb"ascii
$obj5text"\\objautlink"ascii
$obj6text"\\objlink"ascii
$obj7text"\\mmath"ascii

Condition

uint32( 0 ) == 0x74725c7b and ( 1 of ( $ex* ) and 1 of ( $ole* ) and 2 of ( $obj* ) )

In plain words (Heuristic)

  • The file must start with “{\rt” — an RTF document.
  • At least 1 patterns in ( $ex* ) must match.
  • At least 1 patterns in ( $ole* ) must match.
  • At least 2 patterns in ( $obj* ) must match.

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References

Licence & attribution

Author: ditekSHen

Source repository: ditekSHen detection @ e76c93dcde

Licence: BSD 2-Clause License (repository licence)

Copyright notice: Copyright 2021 by ditekSHen (https://github.com/ditekshen/detection).

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 342d10b3-61d2-5fcb-8f4f-1fe45049257b

Tags:FILE

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