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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_APT_Nimbus_Manticore_Agent_May26

Detects Nimbus Manticore (UNC1549) agent implant featuring data exfiltration and remote control.

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Jonathan Peters (Nextron Systems)
Date
2026-05-28
Modified
2026-06-01
Score / Quality
80 / 85

What this rule detects

Detects Nimbus Manticore (UNC1549) agent implant featuring data exfiltration and remote control.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-apt-nimbus-manticore-agent-may26.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_APT_Nimbus_Manticore_Agent_May26 : FILE
{
	meta:
		description = "Detects Nimbus Manticore (UNC1549) agent implant featuring data exfiltration and remote control."
		author = "Jonathan Peters (Nextron Systems)"
		id = "382c2528-3b54-5920-b88c-4871c729d02c"
		date = "2026-05-28"
		modified = "2026-06-01"
		reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_apt35_malware_may26.yar#L49-L69"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "dfa1e3137a032ee8561a1cd5e1a0f71a10bebb36aef7c336c878638a9c1239ee"
		logic_hash = "d4aef73f6fc9ad3e03a05e8ecda01bb7faf83ae40d7393b41a5f619c70a45136"
		score = 80
		quality = 85
		tags = "FILE"

	strings:
		$a1 = "Chrome/146.0.0.0 Safari/537.36" wide
		$a2 = ".azurewebsites.net" wide
		$s1 = "/agent/poll?token=" wide fullword
		$s2 = "/agent/init" wide fullword
		$s3 = "/agent/result" wide fullword

	condition:
		uint16( 0 ) == 0x5a4d and 1 of ( $a* ) and 1 of ( $s* ) or 3 of them
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$a1text"Chrome/146.0.0.0 Safari/537.36"wide
$a2text".azurewebsites.net"wide
$s1text"/agent/poll?token="wide fullword
$s2text"/agent/init"wide fullword
$s3text"/agent/result"wide fullword

Condition

uint16( 0 ) == 0x5a4d and 1 of ( $a* ) and 1 of ( $s* ) or 3 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • At least 1 patterns in ( $a* ) must match.
  • At least 1 patterns in ( $s* ) must match.
  • At least 3 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).

  • dfa1e3137a032ee8561a1cd5e1a0f71a10bebb36aef7c336c878638a9c1239ee

Licence & attribution

Author: Jonathan Peters (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: 382c2528-3b54-5920-b88c-4871c729d02c

Tags:FILE

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