Windows_Trojan_Generic_4fbff084

YARA detection rule by Elastic Security · Elastic License v2

Shellcode found in REF2924, belonging to for now unknown trojan

rule Windows_Trojan_Generic_4fbff084 {
    meta:
        author = "Elastic Security"
        id = "4fbff084-5280-4ff8-9c21-c437207231a5"
        fingerprint = "728d7877e7a16fbb756b1c3b6c90ff3b718f0f750803b6a1549cb32c69be0dfc"
        creation_date = "2023-02-28"
        last_modified = "2023-04-23"
        description = "Shellcode found in REF2924, belonging to for now unknown trojan"
        threat_name = "Windows.Trojan.Generic"
        reference_sample = "7010a69ba77e65e70f4f3f4a10af804e6932c2218ff4abd5f81240026822b401"
        severity = 100
        arch_context = "x86, arm64"
        scan_context = "file, memory"
        license = "Elastic License v2"
        os = "windows"
    strings:
        $string_decryption = { 8A 44 30 ?? 8A CD 88 45 ?? 32 C5 C0 C1 ?? 88 04 3E 0F B6 C5 0F B6 D9 0F AF D8 0F B6 C1 0F B6 D1 88 6D ?? 0F AF D0 0F B6 C5 0F B6 CD 0F AF C8 8A 6D ?? 8A 45 ?? C0 CB ?? 02 D1 32 DA 02 EB 88 6D ?? 38 45 ?? 74 ?? 8B 45 ?? 46 81 FE ?? ?? ?? ?? 7C ?? }
        $thread_start = { E8 ?? ?? ?? ?? 6A ?? 8D 44 24 ?? BB ?? ?? ?? ?? 50 6A ?? 5A 8B CF 89 5C 24 ?? E8 ?? ?? ?? ?? 6A ?? 8D 44 24 ?? 89 5C 24 ?? 50 6A ?? 5A 8B CF E8 ?? ?? ?? ?? 6A ?? 8D 44 24 ?? 89 5C 24 ?? 50 6A ?? 5A 8B CF E8 ?? ?? ?? ?? 6A ?? 8D 44 24 ?? 89 5C 24 ?? 50 6A ?? 5A 8B CF E8 ?? ?? ?? ?? }
        $resolve = { 8B 7A ?? 8D 5D ?? 85 FF 74 ?? 0F B7 0F 8D 7F ?? 8D 41 ?? 83 F8 ?? 77 ?? 83 C1 ?? 0F B7 33 83 C3 ?? 8D 46 ?? 83 F8 ?? 77 ?? 83 C6 ?? 85 C9 }
    condition:
        2 of them
}

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

012ade3d-f9eb-4b80-9a5d-ee3189c29531

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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

[[ reason ]]

What does this mean?

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.

[[ reason ]]

What do these messages mean?

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

[[ currentRule.title ]]

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