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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Chrysalis_Shellcode_Loader_Feb26

Detects shellcode used to load Chrysalis backdoor, seen being used in the compromise of the infrastructure hosting Notepad++ by Chinese APT group Lotus Blossom

MalwareChrysalisSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
X__Junior
Date
2026-02-02
Modified
2026-05-15
Score / Quality
80 / 85

What this rule detects

Detects shellcode used to load Chrysalis backdoor, seen being used in the compromise of the infrastructure hosting Notepad++ by Chinese APT group Lotus Blossom

Associated malware family: Chrysalis.

It defines 2 patterns (0 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-chrysalis-shellcode-loader-feb26.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Chrysalis_Shellcode_Loader_Feb26
{
	meta:
		description = "Detects shellcode used to load Chrysalis backdoor, seen being used in the compromise of the infrastructure hosting Notepad++ by Chinese APT group Lotus Blossom"
		author = "X__Junior"
		id = "4dce8370-19d3-579a-b1c7-7dd9fbe51ee6"
		date = "2026-02-02"
		modified = "2026-05-15"
		reference = "https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/lotusblossom_notepad_exploitation.yar#L17-L31"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "e2e3d78437cf9d48c2b2264e44bb36bc2235834fc45bbb50b5d6867f336711e3"
		logic_hash = "1baf027548cc1f501e2f99d4a337eaafec1e8ac2c48420cbff25c396083b6273"
		score = 80
		quality = 85
		tags = ""

	strings:
		$op1 = { 8B C7 03 D7 83 E0 ?? 47 8A 4C 05 ?? 8A 04 13 02 C1 32 C1 2A C1 88 02 8B 55 ?? 3B FE 7C ?? 8B 5D ?? 8B 45 }
		$op2 = { 03 F8 8B 45 ?? 8B 50 ?? 85 C9 79 ?? 0F B7 C1 EB ?? 8D 41 ?? 03 C3 50 FF 75 ?? FF D2 89 07 85 C0 74 ?? 8B 4D ?? 46 }

	condition:
		1 of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$op1hex{ 8B C7 03 D7 83 E0 ?? 47 8A 4C 05 ?? 8A 04 13 02 C1 32 C1 2A C1 88 02 8B 55 ?? 3B FE 7C ?? 8B 5D ?? 8B 45 }
$op2hex{ 03 F8 8B 45 ?? 8B 50 ?? 85 C9 79 ?? 0F B7 C1 EB ?? 8D 41 ?? 03 C3 50 FF 75 ?? FF D2 89 07 85 C0 74 ?? 8B 4D ?? 46 }

Condition

1 of them

In plain words (Heuristic)

  • At least 1 patterns in the rule 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).

  • e2e3d78437cf9d48c2b2264e44bb36bc2235834fc45bbb50b5d6867f336711e3

Licence & attribution

Author: X__Junior

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: 4dce8370-19d3-579a-b1c7-7dd9fbe51ee6

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