rule win_avcrypt_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.avcrypt."
        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.avcrypt"
        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 = { 837e5000 7467 663bdf 7462 837e4000 7515 ff7650 }
            // n = 7, score = 100
            //   837e5000             | cmp                 dword ptr [esi + 0x50], 0
            //   7467                 | je                  0x69
            //   663bdf               | cmp                 bx, di
            //   7462                 | je                  0x64
            //   837e4000             | cmp                 dword ptr [esi + 0x40], 0
            //   7515                 | jne                 0x17
            //   ff7650               | push                dword ptr [esi + 0x50]

        $sequence_1 = { c645fc0e 837db800 7519 68???????? 8d8d78ffffff e8???????? c645fc0f }
            // n = 7, score = 100
            //   c645fc0e             | mov                 byte ptr [ebp - 4], 0xe
            //   837db800             | cmp                 dword ptr [ebp - 0x48], 0
            //   7519                 | jne                 0x1b
            //   68????????           |                     
            //   8d8d78ffffff         | lea                 ecx, [ebp - 0x88]
            //   e8????????           |                     
            //   c645fc0f             | mov                 byte ptr [ebp - 4], 0xf

        $sequence_2 = { c645fc19 e8???????? 68???????? 8d8dfcfeffff }
            // n = 4, score = 100
            //   c645fc19             | mov                 byte ptr [ebp - 4], 0x19
            //   e8????????           |                     
            //   68????????           |                     
            //   8d8dfcfeffff         | lea                 ecx, [ebp - 0x104]

        $sequence_3 = { e8???????? 83ec18 c645fc01 8bcc 896584 68???????? e8???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   83ec18               | sub                 esp, 0x18
            //   c645fc01             | mov                 byte ptr [ebp - 4], 1
            //   8bcc                 | mov                 ecx, esp
            //   896584               | mov                 dword ptr [ebp - 0x7c], esp
            //   68????????           |                     
            //   e8????????           |                     

        $sequence_4 = { 59 59 6a05 59 be???????? 8d7dd8 f3a5 }
            // n = 7, score = 100
            //   59                   | pop                 ecx
            //   59                   | pop                 ecx
            //   6a05                 | push                5
            //   59                   | pop                 ecx
            //   be????????           |                     
            //   8d7dd8               | lea                 edi, [ebp - 0x28]
            //   f3a5                 | rep movsd           dword ptr es:[edi], dword ptr [esi]

        $sequence_5 = { 8d4590 50 8d4dd8 e8???????? be???????? 56 }
            // n = 6, score = 100
            //   8d4590               | lea                 eax, [ebp - 0x70]
            //   50                   | push                eax
            //   8d4dd8               | lea                 ecx, [ebp - 0x28]
            //   e8????????           |                     
            //   be????????           |                     
            //   56                   | push                esi

        $sequence_6 = { 33c9 eb06 8b08 2bca d1f9 85f6 7404 }
            // n = 7, score = 100
            //   33c9                 | xor                 ecx, ecx
            //   eb06                 | jmp                 8
            //   8b08                 | mov                 ecx, dword ptr [eax]
            //   2bca                 | sub                 ecx, edx
            //   d1f9                 | sar                 ecx, 1
            //   85f6                 | test                esi, esi
            //   7404                 | je                  6

        $sequence_7 = { 57 57 6aff 57 ff15???????? 85c0 790b }
            // n = 7, score = 100
            //   57                   | push                edi
            //   57                   | push                edi
            //   6aff                 | push                -1
            //   57                   | push                edi
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   790b                 | jns                 0xd

        $sequence_8 = { c645fc10 8bcc 8965c8 57 }
            // n = 4, score = 100
            //   c645fc10             | mov                 byte ptr [ebp - 4], 0x10
            //   8bcc                 | mov                 ecx, esp
            //   8965c8               | mov                 dword ptr [ebp - 0x38], esp
            //   57                   | push                edi

        $sequence_9 = { 8965c8 68???????? e8???????? 83ec18 c645fc14 8bcc 68???????? }
            // n = 7, score = 100
            //   8965c8               | mov                 dword ptr [ebp - 0x38], esp
            //   68????????           |                     
            //   e8????????           |                     
            //   83ec18               | sub                 esp, 0x18
            //   c645fc14             | mov                 byte ptr [ebp - 4], 0x14
            //   8bcc                 | mov                 ecx, esp
            //   68????????           |                     

    condition:
        7 of them and filesize < 6160384
}