rule win_nullmixer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.nullmixer."
        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.nullmixer"
        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 = { 0fafc6 01d0 894594 8b45c0 8b7d94 f7e6 89c6 }
            // n = 7, score = 100
            //   0fafc6               | imul                eax, esi
            //   01d0                 | add                 eax, edx
            //   894594               | mov                 dword ptr [ebp - 0x6c], eax
            //   8b45c0               | mov                 eax, dword ptr [ebp - 0x40]
            //   8b7d94               | mov                 edi, dword ptr [ebp - 0x6c]
            //   f7e6                 | mul                 esi
            //   89c6                 | mov                 esi, eax

        $sequence_1 = { 89542414 8d1471 894c2404 8b4dd4 89542408 8d5334 897c2410 }
            // n = 7, score = 100
            //   89542414             | mov                 dword ptr [esp + 0x14], edx
            //   8d1471               | lea                 edx, [ecx + esi*2]
            //   894c2404             | mov                 dword ptr [esp + 4], ecx
            //   8b4dd4               | mov                 ecx, dword ptr [ebp - 0x2c]
            //   89542408             | mov                 dword ptr [esp + 8], edx
            //   8d5334               | lea                 edx, [ebx + 0x34]
            //   897c2410             | mov                 dword ptr [esp + 0x10], edi

        $sequence_2 = { 8d4afe 894808 0fb742fe 6683f8ff 7408 89d8 }
            // n = 6, score = 100
            //   8d4afe               | lea                 ecx, [edx - 2]
            //   894808               | mov                 dword ptr [eax + 8], ecx
            //   0fb742fe             | movzx               eax, word ptr [edx - 2]
            //   6683f8ff             | cmp                 ax, -1
            //   7408                 | je                  0xa
            //   89d8                 | mov                 eax, ebx

        $sequence_3 = { 890424 e8???????? 8345c801 0fb67dce 83ec04 8b4d08 8b4108 }
            // n = 7, score = 100
            //   890424               | mov                 dword ptr [esp], eax
            //   e8????????           |                     
            //   8345c801             | add                 dword ptr [ebp - 0x38], 1
            //   0fb67dce             | movzx               edi, byte ptr [ebp - 0x32]
            //   83ec04               | sub                 esp, 4
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   8b4108               | mov                 eax, dword ptr [ecx + 8]

        $sequence_4 = { 8d5701 399424b0000000 0f8472040000 0fb64f01 89d7 f6044820 7421 }
            // n = 7, score = 100
            //   8d5701               | lea                 edx, [edi + 1]
            //   399424b0000000       | cmp                 dword ptr [esp + 0xb0], edx
            //   0f8472040000         | je                  0x478
            //   0fb64f01             | movzx               ecx, byte ptr [edi + 1]
            //   89d7                 | mov                 edi, edx
            //   f6044820             | test                byte ptr [eax + ecx*2], 0x20
            //   7421                 | je                  0x23

        $sequence_5 = { 891c24 897dd0 e8???????? 8b55d0 8b4dbc 83ec08 8b01 }
            // n = 7, score = 100
            //   891c24               | mov                 dword ptr [esp], ebx
            //   897dd0               | mov                 dword ptr [ebp - 0x30], edi
            //   e8????????           |                     
            //   8b55d0               | mov                 edx, dword ptr [ebp - 0x30]
            //   8b4dbc               | mov                 ecx, dword ptr [ebp - 0x44]
            //   83ec08               | sub                 esp, 8
            //   8b01                 | mov                 eax, dword ptr [ecx]

        $sequence_6 = { 56 53 83ec2c 8b4104 8b742440 8b542444 8b5c2448 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   53                   | push                ebx
            //   83ec2c               | sub                 esp, 0x2c
            //   8b4104               | mov                 eax, dword ptr [ecx + 4]
            //   8b742440             | mov                 esi, dword ptr [esp + 0x40]
            //   8b542444             | mov                 edx, dword ptr [esp + 0x44]
            //   8b5c2448             | mov                 ebx, dword ptr [esp + 0x48]

        $sequence_7 = { e8???????? 89c3 85c0 0f84f5800800 8928 89442404 }
            // n = 6, score = 100
            //   e8????????           |                     
            //   89c3                 | mov                 ebx, eax
            //   85c0                 | test                eax, eax
            //   0f84f5800800         | je                  0x880fb
            //   8928                 | mov                 dword ptr [eax], ebp
            //   89442404             | mov                 dword ptr [esp + 4], eax

        $sequence_8 = { 8b6c2434 8b74243c 8b7c2440 39da 774e 8b442438 8b4004 }
            // n = 7, score = 100
            //   8b6c2434             | mov                 ebp, dword ptr [esp + 0x34]
            //   8b74243c             | mov                 esi, dword ptr [esp + 0x3c]
            //   8b7c2440             | mov                 edi, dword ptr [esp + 0x40]
            //   39da                 | cmp                 edx, ebx
            //   774e                 | ja                  0x50
            //   8b442438             | mov                 eax, dword ptr [esp + 0x38]
            //   8b4004               | mov                 eax, dword ptr [eax + 4]

        $sequence_9 = { 89da 85db 750a ba01000000 bb01000000 85f6 0f8447030000 }
            // n = 7, score = 100
            //   89da                 | mov                 edx, ebx
            //   85db                 | test                ebx, ebx
            //   750a                 | jne                 0xc
            //   ba01000000           | mov                 edx, 1
            //   bb01000000           | mov                 ebx, 1
            //   85f6                 | test                esi, esi
            //   0f8447030000         | je                  0x34d

    condition:
        7 of them and filesize < 2351104
}