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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_Sidewinder_NET_Loader_Aug_2020_1_1

Detected the NET loader used by SideWinder group (August 2020)

APT / threat actorSidewinderSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Arkbird_SOLG
Date
2020-08-24
Modified
2023-12-05
Score / Quality
75 / 83

What this rule detects

Detected the NET loader used by SideWinder group (August 2020)

Associated malware family: Sidewinder.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
apt-sidewinder-net-loader-aug-2020-1-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_APT_Sidewinder_NET_Loader_Aug_2020_1_1 : FILE
{
	meta:
		description = "Detected the NET loader used by SideWinder group (August 2020)"
		author = "Arkbird_SOLG"
		id = "61d96e2a-3a43-586f-85bc-a2c53b1318e6"
		date = "2020-08-24"
		modified = "2023-12-05"
		reference = "https://twitter.com/ShadowChasing1/status/1297902086747598852"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_sidewinder.yar#L4-L22"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "4a0947dd9148b3d5922651a6221afc510afcb0dfa69d08ee69429c4c75d4c8b4"
		logic_hash = "5ee7029143c589f26e6c325e163bfac85507c950f09778bd51ec2bdf4d4263fa"
		score = 75
		quality = 83
		tags = "FILE"

	strings:
		$a1 = "DUSER.dll" fullword wide
		$s1 = "UHJvZ3JhbQ==" fullword wide
		$s2 = "U3RhcnQ=" fullword wide
		$s3 = ".tmp           " fullword wide
		$s4 = "FileRipper" fullword ascii
		$s5 = "copytight @" fullword wide

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 4KB and $a1 and 3 of ( $s* )
}

Strings (6 patterns)

IdentifierTypeValueModifiers
$a1text"DUSER.dll"fullword wide
$s1text"UHJvZ3JhbQ=="fullword wide
$s2text"U3RhcnQ="fullword wide
$s3text".tmp "fullword wide
$s4text"FileRipper"fullword ascii
$s5text"copytight @"fullword wide

Condition

uint16( 0 ) == 0x5a4d and filesize < 4KB and $a1 and 3 of ( $s* )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 4KB (a cheap guard that skips large files).
  • At least 3 patterns in ( $s* ) must match.
  • Pattern $a1 must be present.

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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).

  • 4a0947dd9148b3d5922651a6221afc510afcb0dfa69d08ee69429c4c75d4c8b4

Licence & attribution

Author: Arkbird_SOLG

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: 61d96e2a-3a43-586f-85bc-a2c53b1318e6

Tags:FILE

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