rule win_h1n1_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.h1n1."
        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.h1n1"
        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 = { ff35???????? 58 ffd0 85c0 7452 }
            // n = 5, score = 400
            //   ff35????????         |                     
            //   58                   | pop                 eax
            //   ffd0                 | call                eax
            //   85c0                 | test                eax, eax
            //   7452                 | je                  0x54

        $sequence_1 = { 43 43 e9???????? 83bde8feffff05 7510 83bdecfeffff02 }
            // n = 6, score = 400
            //   43                   | inc                 ebx
            //   43                   | inc                 ebx
            //   e9????????           |                     
            //   83bde8feffff05       | cmp                 dword ptr [ebp - 0x118], 5
            //   7510                 | jne                 0x12
            //   83bdecfeffff02       | cmp                 dword ptr [ebp - 0x114], 2

        $sequence_2 = { 83bdecfeffff02 750a bb08000000 e9???????? 83bde8feffff06 }
            // n = 5, score = 400
            //   83bdecfeffff02       | cmp                 dword ptr [ebp - 0x114], 2
            //   750a                 | jne                 0xc
            //   bb08000000           | mov                 ebx, 8
            //   e9????????           |                     
            //   83bde8feffff06       | cmp                 dword ptr [ebp - 0x118], 6

        $sequence_3 = { 8b7de8 8b75dc 8b4de0 f3a4 ff75fc 8f45e8 8d45e0 }
            // n = 7, score = 400
            //   8b7de8               | mov                 edi, dword ptr [ebp - 0x18]
            //   8b75dc               | mov                 esi, dword ptr [ebp - 0x24]
            //   8b4de0               | mov                 ecx, dword ptr [ebp - 0x20]
            //   f3a4                 | rep movsb           byte ptr es:[edi], byte ptr [esi]
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   8f45e8               | pop                 dword ptr [ebp - 0x18]
            //   8d45e0               | lea                 eax, [ebp - 0x20]

        $sequence_4 = { e8???????? 86e0 8ad4 c0ea02 }
            // n = 4, score = 400
            //   e8????????           |                     
            //   86e0                 | xchg                al, ah
            //   8ad4                 | mov                 dl, ah
            //   c0ea02               | shr                 dl, 2

        $sequence_5 = { 93 5e 5f 5b c9 c21400 55 }
            // n = 7, score = 400
            //   93                   | xchg                eax, ebx
            //   5e                   | pop                 esi
            //   5f                   | pop                 edi
            //   5b                   | pop                 ebx
            //   c9                   | leave               
            //   c21400               | ret                 0x14
            //   55                   | push                ebp

        $sequence_6 = { 55 8bec 83c4f0 57 53 33db c745fc00040000 }
            // n = 7, score = 400
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   83c4f0               | add                 esp, -0x10
            //   57                   | push                edi
            //   53                   | push                ebx
            //   33db                 | xor                 ebx, ebx
            //   c745fc00040000       | mov                 dword ptr [ebp - 4], 0x400

        $sequence_7 = { 6800040000 ff75fc ff35???????? 58 }
            // n = 4, score = 400
            //   6800040000           | push                0x400
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff35????????         |                     
            //   58                   | pop                 eax

        $sequence_8 = { 330c95c0850010 8bc1 83e001 d1e9 }
            // n = 4, score = 100
            //   330c95c0850010       | xor                 ecx, dword ptr [edx*4 + 0x100085c0]
            //   8bc1                 | mov                 eax, ecx
            //   83e001               | and                 eax, 1
            //   d1e9                 | shr                 ecx, 1

        $sequence_9 = { 7cc4 81fa6f020000 7d35 57 8d3c95c0850010 }
            // n = 5, score = 100
            //   7cc4                 | jl                  0xffffffc6
            //   81fa6f020000         | cmp                 edx, 0x26f
            //   7d35                 | jge                 0x37
            //   57                   | push                edi
            //   8d3c95c0850010       | lea                 edi, [edx*4 + 0x100085c0]

        $sequence_10 = { d1e9 330c8500850010 330d???????? 890d???????? 8b0cb5c0850010 8bc1 }
            // n = 6, score = 100
            //   d1e9                 | shr                 ecx, 1
            //   330c8500850010       | xor                 ecx, dword ptr [eax*4 + 0x10008500]
            //   330d????????         |                     
            //   890d????????         |                     
            //   8b0cb5c0850010       | mov                 ecx, dword ptr [esi*4 + 0x100085c0]
            //   8bc1                 | mov                 eax, ecx

        $sequence_11 = { 6a05 8d442420 68e06d0010 03c1 }
            // n = 4, score = 100
            //   6a05                 | push                5
            //   8d442420             | lea                 eax, [esp + 0x20]
            //   68e06d0010           | push                0x10006de0
            //   03c1                 | add                 eax, ecx

        $sequence_12 = { 42 b9c0850010 8b01 c1e81e 3301 }
            // n = 5, score = 100
            //   42                   | inc                 edx
            //   b9c0850010           | mov                 ecx, 0x100085c0
            //   8b01                 | mov                 eax, dword ptr [ecx]
            //   c1e81e               | shr                 eax, 0x1e
            //   3301                 | xor                 eax, dword ptr [ecx]

        $sequence_13 = { 59 84c0 7432 6808610010 ff742408 }
            // n = 5, score = 100
            //   59                   | pop                 ecx
            //   84c0                 | test                al, al
            //   7432                 | je                  0x34
            //   6808610010           | push                0x10006108
            //   ff742408             | push                dword ptr [esp + 8]

        $sequence_14 = { 338774fcffff 33c1 8907 83c704 81ff7c8f0010 7cd4 5f }
            // n = 7, score = 100
            //   338774fcffff         | xor                 eax, dword ptr [edi - 0x38c]
            //   33c1                 | xor                 eax, ecx
            //   8907                 | mov                 dword ptr [edi], eax
            //   83c704               | add                 edi, 4
            //   81ff7c8f0010         | cmp                 edi, 0x10008f7c
            //   7cd4                 | jl                  0xffffffd6
            //   5f                   | pop                 edi

        $sequence_15 = { 8d842460050000 57 50 e8???????? 68f4600010 }
            // n = 5, score = 100
            //   8d842460050000       | lea                 eax, [esp + 0x560]
            //   57                   | push                edi
            //   50                   | push                eax
            //   e8????????           |                     
            //   68f4600010           | push                0x100060f4

    condition:
        7 of them and filesize < 172032
}