rule win_skip20_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.skip20."
        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.skip20"
        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 = { 756d 48895c2450 4885db 7468 488d1579e3ffff }
            // n = 5, score = 200
            //   756d                 | mov                 ebp, ecx
            //   48895c2450           | dec                 eax
            //   4885db               | lea                 ecx, [esp + 0x22]
            //   7468                 | xor                 edi, edi
            //   488d1579e3ffff       | xor                 edx, edx

        $sequence_1 = { 4883f801 0f84d2000000 448b15???????? 4533db }
            // n = 4, score = 200
            //   4883f801             | mov                 ecx, esp
            //   0f84d2000000         | dec                 esp
            //   448b15????????       |                     
            //   4533db               | mov                 eax, edi

        $sequence_2 = { 488b1ccb 488b442458 4d8bcc 4c8bc7 4889442440 }
            // n = 5, score = 200
            //   488b1ccb             | dec                 eax
            //   488b442458           | mov                 ebx, dword ptr [ebx + ecx*8]
            //   4d8bcc               | dec                 eax
            //   4c8bc7               | mov                 eax, dword ptr [esp + 0x58]
            //   4889442440           | dec                 ebp

        $sequence_3 = { 834518fc 0f8810f7ffff 488b4510 486308 48890b }
            // n = 5, score = 200
            //   834518fc             | inc                 ebp
            //   0f8810f7ffff         | xor                 ebx, ebx
            //   488b4510             | dec                 esp
            //   486308               | mov                 esp, edx
            //   48890b               | dec                 eax

        $sequence_4 = { 7468 488d15cde2ffff 488bcb e8???????? }
            // n = 4, score = 200
            //   7468                 | test                ebx, ebx
            //   488d15cde2ffff       | je                  0x6d
            //   488bcb               | dec                 eax
            //   e8????????           |                     

        $sequence_5 = { 4c8be2 488be9 e8???????? 488d4c2422 33ff 33d2 }
            // n = 6, score = 200
            //   4c8be2               | dec                 eax
            //   488be9               | mov                 dword ptr [esp + 0x40], eax
            //   e8????????           |                     
            //   488d4c2422           | dec                 eax
            //   33ff                 | cmp                 eax, 1
            //   33d2                 | je                  0xd8

        $sequence_6 = { 7f95 83bc24c800000001 7511 40f6c610 740b 834f0410 66834b1801 }
            // n = 7, score = 200
            //   7f95                 | add                 dword ptr [ebp + 0x18], -4
            //   83bc24c800000001     | js                  0xfffff71a
            //   7511                 | dec                 eax
            //   40f6c610             | mov                 eax, dword ptr [ebp + 0x10]
            //   740b                 | dec                 eax
            //   834f0410             | arpl                word ptr [eax], cx
            //   66834b1801           | dec                 eax

        $sequence_7 = { e8???????? 8b8424d8000000 c744bb2207300800 4c8d15f490ffff 85c0 7509 }
            // n = 6, score = 200
            //   e8????????           |                     
            //   8b8424d8000000       | mov                 dword ptr [ebx], ecx
            //   c744bb2207300800     | jne                 0x6f
            //   4c8d15f490ffff       | dec                 eax
            //   85c0                 | mov                 dword ptr [esp + 0x50], ebx
            //   7509                 | dec                 eax

    condition:
        7 of them and filesize < 794624
}