YARA · SEKOIA.IO Community

SEKOIA_Apt_Ta410_Flowcloud_Rtti

Detects FlowCloud via RTTI

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X

Author: Sekoia.io
Date: 2022-10-11
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects FlowCloud via RTTI

Targets: Windows PE.

It defines 3 patterns (3 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-ta410-flowcloud-rtti.yarDetection Rule License 1.1

rule SEKOIA_Apt_Ta410_Flowcloud_Rtti : FILE
{
	meta:
		description = "Detects FlowCloud via RTTI"
		author = "Sekoia.io"
		id = "c6a18c08-8b98-46d7-a6c3-dc171c7791ac"
		date = "2022-10-11"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_ta410_flowcloud_rtti.yar#L1-L17"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "97f052c409c9b5de025d34180979cd4c322e67bab9f894d3b56c928340a6859b"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$RTTI_1 = ".?AVdllloader@@" ascii fullword
		$RTTI_2 = ".?AVel_cryptowrapper@@" ascii fullword
		$RTTI_3 = ".?AVAntiVirusCheck@@" ascii fullword

	condition:
		uint16( 0 ) == 0x5A4D and filesize < 10MB and all of them
}

Strings (3 patterns)

Identifier	Type	Value	Modifiers
$RTTI_1	text	".?AVdllloader@@"	ascii fullword
$RTTI_2	text	".?AVel_cryptowrapper@@"	ascii fullword
$RTTI_3	text	".?AVAntiVirusCheck@@"	ascii fullword

Condition

uint16( 0 ) == 0x5A4D and filesize < 10MB and all of them

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 10MB (a cheap guard that skips large files).
All patterns in the rule must match.

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References

https://github.com/SEKOIA-IO/Community

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

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: c6a18c08-8b98-46d7-a6c3-dc171c7791ac

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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