rule win_nokoyawa_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.nokoyawa."
        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.nokoyawa"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        malpedia_license = "CC BY-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

    /* DISCLAIMER
     * The strings used in this rule have been automatically selected from the
     * disassembly of memory dumps and unpacked files, using YARA-Signator.
     * The code and documentation is published here:
     * https://github.com/fxb-cocacoding/yara-signator
     * As Malpedia is used as data source, please note that for a given
     * number of families, only single samples are documented.
     * This likely impacts the degree of generalization these rules will offer.
     * Take the described generation method also into consideration when you
     * apply the rules in your use cases and assign them confidence levels.
     */


    strings:
        $sequence_0 = { ff15???????? 89442448 837c244800 7407 33c0 e9???????? 8b442440 }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   89442448             | dec                 eax
            //   837c244800           | mov                 dword ptr [esp + 8], eax
            //   7407                 | dec                 eax
            //   33c0                 | mov                 eax, dword ptr [esp + 0x10]
            //   e9????????           |                     
            //   8b442440             | mov                 ecx, dword ptr [esp]

        $sequence_1 = { ba20000000 488b4c2448 e8???????? 488b542448 488b4c2458 e8???????? 4c8b442460 }
            // n = 7, score = 100
            //   ba20000000           | cwde                
            //   488b4c2448           | dec                 eax
            //   e8????????           |                     
            //   488b542448           | mov                 edx, eax
            //   488b4c2458           | dec                 eax
            //   e8????????           |                     
            //   4c8b442460           | lea                 ecx, [esp + 0x5c]

        $sequence_2 = { 488b4c2420 4803c8 488bc1 0fbe00 85c0 740d }
            // n = 6, score = 100
            //   488b4c2420           | mov                 ecx, dword ptr [esp + 0x14]
            //   4803c8               | mov                 ecx, 4
            //   488bc1               | dec                 eax
            //   0fbe00               | imul                ecx, ecx, 0xb
            //   85c0                 | xor                 eax, dword ptr [esp + ecx + 0x20]
            //   740d                 | mov                 dword ptr [esp], eax

        $sequence_3 = { eb0b 8b442420 83c014 89442420 837c242040 7d56 c744242400000000 }
            // n = 7, score = 100
            //   eb0b                 | dec                 eax
            //   8b442420             | mov                 ecx, dword ptr [esp + 0x48]
            //   83c014               | test                eax, eax
            //   89442420             | dec                 eax
            //   837c242040           | sub                 esp, 0x38
            //   7d56                 | dec                 eax
            //   c744242400000000     | mov                 eax, dword ptr [esp + 0x48]

        $sequence_4 = { 89442408 488b442418 48ffc0 4889442418 837c24083f 7f02 ebd3 }
            // n = 7, score = 100
            //   89442408             | or                  edx, ecx
            //   488b442418           | mov                 ecx, edx
            //   48ffc0               | mov                 edx, dword ptr [esp + 0x10c]
            //   4889442418           | shr                 ecx, 0x1b
            //   837c24083f           | mov                 edx, dword ptr [esp + 0x10]
            //   7f02                 | shl                 edx, 5
            //   ebd3                 | or                  edx, ecx

        $sequence_5 = { 33d1 8bca 03c1 b904000000 486bc90a 8b4c0c20 }
            // n = 6, score = 100
            //   33d1                 | mov                 ecx, dword ptr [esp + 0x30]
            //   8bca                 | mov                 dword ptr [ecx], eax
            //   03c1                 | mov                 ecx, dword ptr [ecx]
            //   b904000000           | xor                 ecx, eax
            //   486bc90a             | mov                 eax, ecx
            //   8b4c0c20             | dec                 eax

        $sequence_6 = { 0f84a4000000 488d4c245c e8???????? 4898 488bd0 488d4c245c e8???????? }
            // n = 7, score = 100
            //   0f84a4000000         | dec                 eax
            //   488d4c245c           | lea                 edx, [esp + 0x20]
            //   e8????????           |                     
            //   4898                 | dec                 eax
            //   488bd0               | lea                 ecx, [esp + 0x20]
            //   488d4c245c           | dec                 esp
            //   e8????????           |                     

        $sequence_7 = { 482b442430 483b442468 760c 488b442468 4889442438 eb0f }
            // n = 6, score = 100
            //   482b442430           | arpl                word ptr [esp], ax
            //   483b442468           | dec                 eax
            //   760c                 | mov                 ecx, dword ptr [esp + 0x30]
            //   488b442468           | mov                 eax, dword ptr [esp + 0xc]
            //   4889442438           | mov                 ecx, dword ptr [esp + 8]
            //   eb0f                 | or                  ecx, eax

        $sequence_8 = { eb0d 0fb7442420 66ffc0 6689442420 0fb7442420 83f85a 0f8f81000000 }
            // n = 7, score = 100
            //   eb0d                 | dec                 eax
            //   0fb7442420           | lea                 eax, [eax*8 + 8]
            //   66ffc0               | dec                 eax
            //   6689442420           | mov                 ecx, eax
            //   0fb7442420           | dec                 eax
            //   83f85a               | sub                 esp, 0x38
            //   0f8f81000000         | dec                 eax

        $sequence_9 = { 0bd1 8bca 8b9424c4000000 03d1 8bca 8d8408a1ebd96e 8b4c2404 }
            // n = 7, score = 100
            //   0bd1                 | lea                 ecx, [esp + 0x6a0]
            //   8bca                 | dec                 eax
            //   8b9424c4000000       | lea                 ecx, [esp + 0x5c]
            //   03d1                 | dec                 eax
            //   8bca                 | cwde                
            //   8d8408a1ebd96e       | dec                 eax
            //   8b4c2404             | mov                 edx, eax

    condition:
        7 of them and filesize < 92160
}