YARA · Mandiant red team tool countermeasures

FIREEYE_RT_Builder_MSIL_G2JS_1

The TypeLibGUID present in a .NET binary maps directly to the ProjectGuid found in the '.csproj' file of a .NET project. This rule looks for .NET PE files that contain the ProjectGuid found in the Gadget2JScript project.

GenericMandiant red team tool countermeasuresBSD 2-Clause LicenseCompiles with YARA-X

Author: FireEye
Date: 2020-12-08
Modified: 2020-12-09
Score / Quality: 75 / 73

What this rule detects

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

builder-msil-g2js-1.yarBSD 2-Clause License

rule FIREEYE_RT_Builder_MSIL_G2JS_1 : FILE
{
	meta:
		description = "The TypeLibGUID present in a .NET binary maps directly to the ProjectGuid found in the '.csproj' file of a .NET project. This rule looks for .NET PE files that contain the ProjectGuid found in the Gadget2JScript project."
		author = "FireEye"
		id = "484202c2-ac7d-5e6c-8bf1-3452a357c668"
		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/G2JS/production/yara/Builder_MSIL_G2JS_1.yar#L4-L15"
		license_url = "https://github.com/mandiant/red_team_tool_countermeasures//blob/3561b71724dbfa3e2bb78106aaa2d7f8b892c43b/LICENSE.txt"
		hash = "fa255fdc88ab656ad9bc383f9b322a76"
		logic_hash = "487d8e8deef218412f241d99ce32b63bfeb3568d23048b9dd4afff8f401bfea5"
		score = 75
		quality = 73
		tags = "FILE"
		rev = 2

	strings:
		$typelibguid1 = "AF9C62A1-F8D2-4BE0-B019-0A7873E81EA9" ascii nocase wide

	condition:
		( uint16( 0 ) == 0x5A4D and uint32( uint32( 0x3C ) ) == 0x00004550 ) and $typelibguid1
}

Strings (1 patterns)

Identifier	Type	Value	Modifiers
$typelibguid1	text	"AF9C62A1-F8D2-4BE0-B019-0A7873E81EA9"	ascii nocase wide

Condition

( uint16( 0 ) == 0x5A4D and uint32( uint32( 0x3C ) ) == 0x00004550 ) and $typelibguid1

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
Pattern $typelibguid1 must be present.

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References

https://github.com/mandiant/red_team_tool_countermeasures/

Sample hashes

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

fa255fdc88ab656ad9bc383f9b322a76

Licence & attribution

Author: FireEye

Source repository: Mandiant red team tool countermeasures @ 3561b71724

Licence: BSD 2-Clause License (repository licence)

Original rule

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

Rule id: 484202c2-ac7d-5e6c-8bf1-3452a357c668

Metadata

rev	2

Tags:FILE

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