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SEKOIA_Apt_Unc4990_Explorer_Ps1

Detects powershell script (explorer.ps1)

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2024-02-01
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detects powershell script (explorer.ps1)

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

Summary generated from the rule's metadata and condition.

Rule source

apt-unc4990-explorer-ps1.yarDetection Rule License 1.1
rule SEKOIA_Apt_Unc4990_Explorer_Ps1
{
	meta:
		description = "Detects powershell script (explorer.ps1)"
		author = "Sekoia.io"
		id = "2e1abbbf-f9b7-4147-b7da-3544cbc4a5f1"
		date = "2024-02-01"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_unc4990_explorer_ps1.yar#L1-L19"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "5085f738e23b801c7e36408d189755086d91c0bb266af6738c80510eb85e598f"
		score = 75
		quality = 80
		tags = ""
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s0 = "$(get-location).Path"
		$s1 = "+ \"\\Runtime Broker.exe"
		$s2 = "Start-Process -FilePath"
		$s3 = "-Wait;"
		$s4 = "Start-Sleep -s"

	condition:
		all of them and @s3- @s2 < 35
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$s0text"$(get-location).Path"
$s1text"+ \"\\Runtime Broker.exe"
$s2text"Start-Process -FilePath"
$s3text"-Wait;"
$s4text"Start-Sleep -s"

Condition

all of them and @s3- @s2 < 35

In plain words (Heuristic)

  • All patterns in the rule 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: 2e1abbbf-f9b7-4147-b7da-3544cbc4a5f1

Metadata

version1.0
classificationTLP:CLEAR