TTP_RegOpenKeyExA_HKEY_USERS_loose

YARA detection rule by @captainGeech42,@stvemillertime,@greglesnewich · GPL-2.0

Look for PE files that try to open HKEY_USERS keys (const 0x80000003) with RegOpenKeyExA

import "pe"
rule TTP_RegOpenKeyExA_HKEY_USERS_loose {
    meta:
        author = "@captainGeech42,@stvemillertime,@greglesnewich"
        description = "Look for PE files that try to open HKEY_USERS keys (const 0x80000003) with RegOpenKeyExA"
        reference = "https://learn.microsoft.com/en-us/windows/win32/sysinfo/predefined-keys"
        date = "2024-01-27"
        version = "1"
        DaysofYARA = "27/100"
    strings:

        $reg_open_key_call = {03 00 00 80 [1-20] ff 15}
    condition:
        uint16be(0) == 0x4d5a and (
            $reg_open_key_call and
            for any i in (1..#reg_open_key_call): (
            for any imp in pe.import_details : (
                imp.library_name == "ADVAPI32.dll" and
                for any func in imp.functions : (
                    func.name == "RegOpenKeyExA" and
                    uint32(@reg_open_key_call[i]+!reg_open_key_call[i])&0xfffff == func.rva                     )
                )
            )
        )
}

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

e621097f-78d3-4f8e-97da-b1e7419c422a

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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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