rule win_opachki_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.opachki."
        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.opachki"
        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 = { c64401ff00 8b4608 85c0 7410 }
            // n = 4, score = 300
            //   c64401ff00           | mov                 byte ptr [ecx + eax - 1], 0
            //   8b4608               | mov                 eax, dword ptr [esi + 8]
            //   85c0                 | test                eax, eax
            //   7410                 | je                  0x12

        $sequence_1 = { 897d0c 7422 8bd7 2bd7 035508 837d0c00 742e }
            // n = 7, score = 300
            //   897d0c               | mov                 dword ptr [ebp + 0xc], edi
            //   7422                 | je                  0x24
            //   8bd7                 | mov                 edx, edi
            //   2bd7                 | sub                 edx, edi
            //   035508               | add                 edx, dword ptr [ebp + 8]
            //   837d0c00             | cmp                 dword ptr [ebp + 0xc], 0
            //   742e                 | je                  0x30

        $sequence_2 = { 8bd8 7413 8b4704 03c8 }
            // n = 4, score = 300
            //   8bd8                 | mov                 ebx, eax
            //   7413                 | je                  0x15
            //   8b4704               | mov                 eax, dword ptr [edi + 4]
            //   03c8                 | add                 ecx, eax

        $sequence_3 = { c706???????? 894608 89460c 894604 e8???????? 8bc6 }
            // n = 6, score = 300
            //   c706????????         |                     
            //   894608               | mov                 dword ptr [esi + 8], eax
            //   89460c               | mov                 dword ptr [esi + 0xc], eax
            //   894604               | mov                 dword ptr [esi + 4], eax
            //   e8????????           |                     
            //   8bc6                 | mov                 eax, esi

        $sequence_4 = { 6a01 c645ff01 49 81e1feffff3f }
            // n = 4, score = 300
            //   6a01                 | push                1
            //   c645ff01             | mov                 byte ptr [ebp - 1], 1
            //   49                   | dec                 ecx
            //   81e1feffff3f         | and                 ecx, 0x3ffffffe

        $sequence_5 = { c3 55 8bec 81ec00010000 ff7508 }
            // n = 5, score = 300
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   81ec00010000         | sub                 esp, 0x100
            //   ff7508               | push                dword ptr [ebp + 8]

        $sequence_6 = { 81ec20010000 53 56 68ff000000 8d85e0feffff }
            // n = 5, score = 300
            //   81ec20010000         | sub                 esp, 0x120
            //   53                   | push                ebx
            //   56                   | push                esi
            //   68ff000000           | push                0xff
            //   8d85e0feffff         | lea                 eax, [ebp - 0x120]

        $sequence_7 = { 52 51 50 56 ff15???????? 85c0 0f9545ff }
            // n = 7, score = 300
            //   52                   | push                edx
            //   51                   | push                ecx
            //   50                   | push                eax
            //   56                   | push                esi
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   0f9545ff             | setne               byte ptr [ebp - 1]

        $sequence_8 = { 80fd01 7502 b701 80fd02 750a 08db }
            // n = 6, score = 200
            //   80fd01               | cmp                 ch, 1
            //   7502                 | jne                 4
            //   b701                 | mov                 bh, 1
            //   80fd02               | cmp                 ch, 2
            //   750a                 | jne                 0xc
            //   08db                 | or                  bl, bl

        $sequence_9 = { 7702 88da 88c6 80e603 }
            // n = 4, score = 200
            //   7702                 | ja                  4
            //   88da                 | mov                 dl, bl
            //   88c6                 | mov                 dh, al
            //   80e603               | and                 dh, 3

        $sequence_10 = { ad 894721 eb3f 08d2 7408 }
            // n = 5, score = 200
            //   ad                   | lodsd               eax, dword ptr [esi]
            //   894721               | mov                 dword ptr [edi + 0x21], eax
            //   eb3f                 | jmp                 0x41
            //   08d2                 | or                  dl, dl
            //   7408                 | je                  0xa

        $sequence_11 = { e8???????? 59 81c157010000 3c0f 7509 }
            // n = 5, score = 200
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   81c157010000         | add                 ecx, 0x157
            //   3c0f                 | cmp                 al, 0xf
            //   7509                 | jne                 0xb

        $sequence_12 = { 08ed 7405 80fd02 7502 b704 4e 80ff01 }
            // n = 7, score = 200
            //   08ed                 | or                  ch, ch
            //   7405                 | je                  7
            //   80fd02               | cmp                 ch, 2
            //   7502                 | jne                 4
            //   b704                 | mov                 bh, 4
            //   4e                   | dec                 esi
            //   80ff01               | cmp                 bh, 1

        $sequence_13 = { 7505 884702 ebe9 3c2e 7414 }
            // n = 5, score = 200
            //   7505                 | jne                 7
            //   884702               | mov                 byte ptr [edi + 2], al
            //   ebe9                 | jmp                 0xffffffeb
            //   3c2e                 | cmp                 al, 0x2e
            //   7414                 | je                  0x16

        $sequence_14 = { 884701 ebf2 3cf0 7505 }
            // n = 4, score = 200
            //   884701               | mov                 byte ptr [edi + 1], al
            //   ebf2                 | jmp                 0xfffffff4
            //   3cf0                 | cmp                 al, 0xf0
            //   7505                 | jne                 7

    condition:
        7 of them and filesize < 122880
}