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SEKOIA_Apt_Muddywater_Rotrot_Strings

Detects RotRot backdoor based on strings

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2024-06-10
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detects RotRot backdoor based on strings

Targets: Windows PE.

It defines 18 patterns (18 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

apt-muddywater-rotrot-strings.yarDetection Rule License 1.1
rule SEKOIA_Apt_Muddywater_Rotrot_Strings : FILE
{
	meta:
		description = "Detects RotRot backdoor based on strings"
		author = "Sekoia.io"
		id = "f7bc195a-0e60-4495-b78a-78f101543700"
		date = "2024-06-10"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_muddywater_rotrot_strings.yar#L1-L36"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "425168003d0f14d791e7f46bf47c18652a1f6b66b9329155d2bca72cf0d8126b"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s1 = "qsphsbnebub"
		$s2 = "rtqitcofcvc"
		$s3 = "surjudpgdwd"
		$s4 = "tvskveqhexe"
		$s5 = "uwtlwfrifyf"
		$s6 = "vxumxgsjgzg"
		$t1 = "MpbeMjcsbs"
		$t2 = "NqcfNkdtct"
		$t3 = "OrdgOleudu"
		$t4 = "PsehPmfvev"
		$t5 = "QtfiQngwfw"
		$t6 = "RugjRohxgx"
		$u1 = "UfsnjobufKpcPckfdu"
		$u2 = "VgtokpcvgLqdQdlgev"
		$u3 = "WhuplqdwhMreRemhfw"
		$u4 = "XivqmrexiNsfSfnigx"
		$u5 = "YjwrnsfyjOtgTgojhy"
		$u6 = "ZkxsotgzkPuhUhpkiz"

	condition:
		uint16be( 0 ) == 0x4d5a and filesize > 100KB and filesize < 300KB and any of ( $s* ) and any of ( $t* ) and any of ( $u* )
}

Strings (18 patterns)

IdentifierTypeValueModifiers
$s1text"qsphsbnebub"
$s2text"rtqitcofcvc"
$s3text"surjudpgdwd"
$s4text"tvskveqhexe"
$s5text"uwtlwfrifyf"
$s6text"vxumxgsjgzg"
$t1text"MpbeMjcsbs"
$t2text"NqcfNkdtct"
$t3text"OrdgOleudu"
$t4text"PsehPmfvev"
$t5text"QtfiQngwfw"
$t6text"RugjRohxgx"
$u1text"UfsnjobufKpcPckfdu"
$u2text"VgtokpcvgLqdQdlgev"
$u3text"WhuplqdwhMreRemhfw"
$u4text"XivqmrexiNsfSfnigx"
$u5text"YjwrnsfyjOtgTgojhy"
$u6text"ZkxsotgzkPuhUhpkiz"

Condition

uint16be( 0 ) == 0x4d5a and filesize > 100KB and filesize < 300KB and any of ( $s* ) and any of ( $t* ) and any of ( $u* )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 300KB (a cheap guard that skips large files).
  • The file must be larger than 100KB.
  • At least one pattern in ( $s* ) must match.
  • At least one pattern in ( $t* ) must match.
  • At least one pattern in ( $u* ) must match.

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References

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: f7bc195a-0e60-4495-b78a-78f101543700

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE