rule win_nokoyawa_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        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 = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 41b801000000 488d542428 488d4c2428 e8???????? bae9000000 488d4c2428 e8???????? }
            // n = 7, score = 100
            //   41b801000000         | mov                 edx, 0x40
            //   488d542428           | dec                 eax
            //   488d4c2428           | lea                 ecx, [esp + 0x50]
            //   e8????????           |                     
            //   bae9000000           | dec                 esp
            //   488d4c2428           | lea                 eax, [esp + 0x130]
            //   e8????????           |                     

        $sequence_1 = { 0bd1 8bca 8b9424e4000000 03d1 }
            // n = 4, score = 100
            //   0bd1                 | or                  edx, ecx
            //   8bca                 | mov                 ecx, edx
            //   8b9424e4000000       | mov                 edx, dword ptr [esp + 0x150]
            //   03d1                 | add                 edx, ecx

        $sequence_2 = { 817c244403010000 7402 eb0e 817c244403010000 0f850fffffff 488b4c2438 }
            // n = 6, score = 100
            //   817c244403010000     | dec                 eax
            //   7402                 | mov                 ecx, dword ptr [esp + 0x40]
            //   eb0e                 | mov                 ecx, dword ptr [ecx]
            //   817c244403010000     | add                 eax, dword ptr [ecx]
            //   0f850fffffff         | mov                 edx, 0xd
            //   488b4c2438           | mov                 ecx, eax

        $sequence_3 = { e9???????? 8b442440 448bc0 33d2 488b4c2438 e8???????? }
            // n = 6, score = 100
            //   e9????????           |                     
            //   8b442440             | mov                 eax, dword ptr [esp + 0x40]
            //   448bc0               | dec                 eax
            //   33d2                 | mov                 ecx, dword ptr [esp + 0x50]
            //   488b4c2438           | dec                 eax
            //   e8????????           |                     

        $sequence_4 = { 894c0420 8b442404 8b4c2414 0bc8 8bc1 8b4c2408 23c8 }
            // n = 7, score = 100
            //   894c0420             | shr                 ecx, 0x1f
            //   8b442404             | or                  eax, ecx
            //   8b4c2414             | mov                 dword ptr [esp + 0xb4], eax
            //   0bc8                 | mov                 eax, 4
            //   8bc1                 | dec                 eax
            //   8b4c2408             | imul                eax, eax, 3
            //   23c8                 | mov                 ecx, dword ptr [esp + 0xb4]

        $sequence_5 = { 81e100ff0000 0bc1 488b4c2468 8b09 c1e918 }
            // n = 5, score = 100
            //   81e100ff0000         | inc                 esp
            //   0bc1                 | mov                 eax, dword ptr [esp + 0x20]
            //   488b4c2468           | dec                 eax
            //   8b09                 | imul                eax, eax, 0x30
            //   c1e918               | dec                 eax

        $sequence_6 = { 8b4c2408 03c8 8bc1 89442408 8b442410 }
            // n = 5, score = 100
            //   8b4c2408             | cmp                 dword ptr [esp + 8], 0x3f
            //   03c8                 | jg                  0xd90
            //   8bc1                 | dec                 eax
            //   89442408             | mov                 eax, dword ptr [esp + 0x20]
            //   8b442410             | movzx               eax, word ptr [eax]

        $sequence_7 = { b808000000 486bc001 488d15fb700000 488b4c2448 488b0c01 e8???????? }
            // n = 6, score = 100
            //   b808000000           | dec                 eax
            //   486bc001             | mov                 dword ptr [esp + 8], eax
            //   488d15fb700000       | dec                 eax
            //   488b4c2448           | mov                 eax, dword ptr [esp + 0x38]
            //   488b0c01             | dec                 eax
            //   e8????????           |                     

        $sequence_8 = { 33c0 85c0 0f8528ffffff b804000000 486bc00a }
            // n = 5, score = 100
            //   33c0                 | dec                 eax
            //   85c0                 | mov                 ecx, dword ptr [esp + 0x48]
            //   0f8528ffffff         | mov                 eax, 0x43
            //   b804000000           | mov                 word ptr [esp + 0x20], ax
            //   486bc00a             | jmp                 0x1769

        $sequence_9 = { eb6f c644242201 c644242101 0fb6442420 85c0 7424 8b442424 }
            // n = 7, score = 100
            //   eb6f                 | dec                 eax
            //   c644242201           | mov                 eax, dword ptr [esp + 0x10]
            //   c644242101           | dec                 eax
            //   0fb6442420           | add                 eax, 2
            //   85c0                 | dec                 eax
            //   7424                 | sub                 eax, 4
            //   8b442424             | dec                 eax

    condition:
        7 of them and filesize < 92160
}