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YARA · Mandiant red team tool countermeasures

FIREEYE_RT_Dropper_HTA_Wildchild_1

This rule looks for strings present in unobfuscated HTAs generated by the WildChild builder.

MalwareMandiant red team tool countermeasuresBSD 2-Clause LicenseCompiles with YARA-X (with warnings)
Author
FireEye
Date
2020-12-08
Modified
2020-12-09
Score / Quality
75 / 75

What this rule detects

This rule looks for strings present in unobfuscated HTAs generated by the WildChild builder.

It defines 10 patterns (10 text, 0 hex, 0 regex).

YARA-X says: warning[unintended_pattern_in_set]: pattern `$script_header` may be unintendedly or redundantly included in pattern set `$s*`

Summary generated from the rule's metadata and condition.

Rule source

dropper-hta-wildchild-1.yarBSD 2-Clause License
rule FIREEYE_RT_Dropper_HTA_Wildchild_1 : FILE
{
	meta:
		description = "This rule looks for strings present in unobfuscated HTAs generated by the WildChild builder."
		author = "FireEye"
		id = "f570baa5-7d58-5a0a-b713-769e62076f76"
		date = "2020-12-08"
		modified = "2020-12-09"
		reference = "https://github.com/mandiant/red_team_tool_countermeasures/"
		source_url = "https://github.com/mandiant/red_team_tool_countermeasures//blob/3561b71724dbfa3e2bb78106aaa2d7f8b892c43b/rules/WILDCHILD/production/yara/Dropper_HTA_WildChild_1.yar#L4-L24"
		license_url = "https://github.com/mandiant/red_team_tool_countermeasures//blob/3561b71724dbfa3e2bb78106aaa2d7f8b892c43b/LICENSE.txt"
		hash = "3e61ca5057633459e96897f79970a46d"
		logic_hash = "60c1d53b8a43b9b7518f3260a4d61c6806641ee894a2a331a3a0a2ea0aff9d99"
		score = 75
		quality = 75
		tags = "FILE"
		rev = 5

	strings:
		$s1 = "processpath" ascii wide
		$s2 = "v4.0.30319" ascii wide
		$s3 = "v2.0.50727" ascii wide
		$s4 = "COMPLUS_Version" ascii wide
		$s5 = "FromBase64Transform" ascii wide
		$s6 = "MemoryStream" ascii wide
		$s7 = "entry_class" ascii wide
		$s8 = "DynamicInvoke" ascii wide
		$s9 = "Sendoff" ascii wide
		$script_header = "<script language=" ascii wide

	condition:
		$script_header at 0 and all of ( $s* )
}

Strings (10 patterns)

IdentifierTypeValueModifiers
$s1text"processpath"ascii wide
$s2text"v4.0.30319"ascii wide
$s3text"v2.0.50727"ascii wide
$s4text"COMPLUS_Version"ascii wide
$s5text"FromBase64Transform"ascii wide
$s6text"MemoryStream"ascii wide
$s7text"entry_class"ascii wide
$s8text"DynamicInvoke"ascii wide
$s9text"Sendoff"ascii wide
$script_headertext"<script language="ascii wide

Condition

$script_header at 0 and all of ( $s* )

In plain words (Heuristic)

  • All patterns in ( $s* ) must match.
  • Pattern $script_header must be found at offset 0.

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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).

  • 3e61ca5057633459e96897f79970a46d

Licence & attribution

Author: FireEye

Source repository: Mandiant red team tool countermeasures @ 3561b71724

Licence: BSD 2-Clause License (repository licence)

Copyright notice: Copyright (c) 2023, MANDIANT

Original rule

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

Rule id: f570baa5-7d58-5a0a-b713-769e62076f76

Metadata

rev5

Tags:FILE