win_formbook_auto

YARA detection rule by Felix Bilstein - yara-signator at cocacoding dot com

Detects win.formbook.

rule win_formbook_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.formbook."
        info = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.6.0"
        signator_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.formbook"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        malpedia_license = "CC BY-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

    


    strings:
        $sequence_0 = { 5b 03f1 5f c6040600 }
                                                            
        $sequence_1 = { 8b10 8d4d0c 51 52 50 e8???????? 83c418 }
                                                                                                
        $sequence_2 = { 85c0 7458 56 33f6 803b00 7413 46 }
                                                                                                
        $sequence_3 = { e8???????? 53 8d55ec 52 8b16 8d85d8fcffff 50 }
                                                                                                
        $sequence_4 = { e8???????? 8b45fc 50 57 e8???????? 8d8d50ffffff 8bd1 }
                                                                                                
        $sequence_5 = { 7439 8b4514 8d4814 51 8d908c020000 52 8d8820020000 }
                                                                                                
        $sequence_6 = { 894df8 e8???????? 830702 83c40c 830603 8b06 8a4c1801 }
                                                                                                
        $sequence_7 = { 83c404 3bfe 72ef 8b45fc 8b7d10 8b8f40020000 8b5514 }
                                                                                                
        $sequence_8 = { 813b50450000 7408 5f 33c0 5b }
                                                                        
        $sequence_9 = { 89948db8feffff 0fb65007 c1e208 0bd7 0fb67809 c1e208 0bd7 }
                                                                                                
    condition:
        7 of them and filesize < 371712
}

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

7ca7451a-5a82-415f-9016-f8e7004eff8b

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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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