Obfs_behavior_wmi

YARA detection rule by k3rnelcallz · MIT

detection for JS Loader focusing on WMI/ADSI discovery and XOR loops

rule Obfs_behavior_wmi {
    meta:
        description = "detection for JS Loader focusing on WMI/ADSI discovery and XOR loops"
        author = "k3rnelcallz"
        reference = "malwarebazaar"
        sha = "2e5934e38666e63c23f5906e5175a1bf5c230972cb57bb8c07dab0630921fa43"

    strings:
        
        $xor_math = { 2A [1-10] 2B [1-10] 26 20 32 35 35 } 

        
        $obj1 = "Schedule.Service"
        $obj2 = "Win32_Process"
        $obj3 = "ADODB.Stream"
        $obj4 = "OpenDSObject"          
        
        $sid_admin = "-512"              $stealth = "ShowWindow = 0"
        $rand_seed = "Math.random() * 900000"

    condition:
        (filesize < 300KB) and ($xor_math and 2 of ($obj*, $sid_admin, $stealth, $rand_seed))
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

2969955c-e386-4c81-8921-ab8d55236fec

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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