YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_HKTL_Bluehammer_Apr26

Detects Nightmare-Eclipse/BlueHammer (FunnyApp), a Windows local privilege escalation PoC that abuses a Defender signature-update RPC and a junction/symlink race to leak the SAM hive and derive NTLM hashes - giving an unprivileged user full SYSTEM-level credential access.

Hack toolSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X

Author: AzizFarghly (Nextron-Systems)
Date: 2026-04-07
Modified: 2026-05-15
Score / Quality: 90 / 85

What this rule detects

Targets: Windows PE.

It defines 6 patterns (5 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

hktl-bluehammer-apr26.yarDetection Rule License 1.1

rule SIGNATURE_BASE_HKTL_Bluehammer_Apr26 : FILE
{
	meta:
		description = "Detects Nightmare-Eclipse/BlueHammer (FunnyApp), a Windows local privilege escalation PoC that abuses a Defender signature-update RPC and a junction/symlink race to leak the SAM hive and derive NTLM hashes - giving an unprivileged user full SYSTEM-level credential access."
		author = "AzizFarghly (Nextron-Systems)"
		id = "595bf733-b287-5048-88e2-b88caffc7a5d"
		date = "2026-04-07"
		modified = "2026-05-15"
		reference = "https://github.com/Nightmare-Eclipse/BlueHammer"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/htkl_blue_hammer_tool.yar#L1-L35"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "6514f56223999eb86a19ea9f2abbfb0f407934a1a0694ffb94a8ea37113073f4"
		hash = "93008c42764b74b759678fd376abd90696f74af408600727b6649286d8424270"
		hash = "b25e903988e530df00658ff3ad6d180e43d6660b705ad6d0def4a29ee1167e52"
		hash = "82eb727e2a2b3334a70fa2d357ba4f44dc989a650a6a18222dd5d1bb1444b496"
		hash = "b33f3f31c83fc655952fab73d72b673b92ed4f205daee56444903201316cfc4a"
		hash = "c6baa5ec9ea2c2802a90acad5a53453d176a02e04a31ac8e9b7b34b5e3329b84"
		hash = "552dba31a446e96416738d84d4366503c397ba508a732719531c89a41abf3704"
		hash = "c9bec499db6a0a2165bcd2a211c8887e5fadf954eb9a2e5d3c6ca833e4a5ef64"
		logic_hash = "fa5f566895d158f1ae07f282fc19516792e620855a9485026ab05f359c48f670"
		score = 90
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "Junction created %ws => %ws"
		$x2 = "connect to windows defender RPC port !!!"
		$s1 = "\\System32\\Config\\SAM" wide
		$s2 = "IMpService77BDAF73-B396-481F-9042-AD358843EC24" wide
		$s3 = "ServerMpUpdateEngineSignature"
		$op1 = { 8D 47 02 66 89 43 0C 66 C7 43 0E 02 00 48 8B C7 48 D1 E8 66 44 89 7C 43 12 }

	condition:
		uint16( 0 ) == 0x5A4D and filesize < 7MB and ( 1 of ( $x* ) or all of ( $s* ) or $op1 ) or 3 of them
}

Strings (6 patterns)

Identifier	Type	Value	Modifiers
$x1	text	"Junction created %ws => %ws"
$x2	text	"connect to windows defender RPC port !!!"
$s1	text	"\\System32\\Config\\SAM"	wide
$s2	text	"IMpService77BDAF73-B396-481F-9042-AD358843EC24"	wide
$s3	text	"ServerMpUpdateEngineSignature"
$op1	hex	{ 8D 47 02 66 89 43 0C 66 C7 43 0E 02 00 48 8B C7 48 D1 E8 66 44 89 7C 43 12 }

Condition

uint16( 0 ) == 0x5A4D and filesize < 7MB and ( 1 of ( $x* ) or all of ( $s* ) or $op1 ) or 3 of them

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 7MB (a cheap guard that skips large files).
All patterns in ( $s* ) must match.
At least 1 patterns in ( $x* ) must match.
At least 3 patterns in the rule must match.
Pattern $op1 must be present.

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References

https://github.com/Nightmare-Eclipse/BlueHammer

Sample hashes

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

6514f56223999eb86a19ea9f2abbfb0f407934a1a0694ffb94a8ea37113073f4
93008c42764b74b759678fd376abd90696f74af408600727b6649286d8424270
b25e903988e530df00658ff3ad6d180e43d6660b705ad6d0def4a29ee1167e52
82eb727e2a2b3334a70fa2d357ba4f44dc989a650a6a18222dd5d1bb1444b496
b33f3f31c83fc655952fab73d72b673b92ed4f205daee56444903201316cfc4a
c6baa5ec9ea2c2802a90acad5a53453d176a02e04a31ac8e9b7b34b5e3329b84
552dba31a446e96416738d84d4366503c397ba508a732719531c89a41abf3704
c9bec499db6a0a2165bcd2a211c8887e5fadf954eb9a2e5d3c6ca833e4a5ef64

Licence & attribution

Author: AzizFarghly (Nextron-Systems)

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: 595bf733-b287-5048-88e2-b88caffc7a5d

Tags:FILE