rule win_bka_trojaner_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.bka_trojaner."
        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.bka_trojaner"
        malpedia_rule_date = "20260422"
        malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
        malpedia_version = "20260504"
        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 = { e8???????? 8bf0 ff15???????? 85f6 89442408 744c 53 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   ff15????????         |                     
            //   85f6                 | test                esi, esi
            //   89442408             | mov                 dword ptr [esp + 8], eax
            //   744c                 | je                  0x4e
            //   53                   | push                ebx

        $sequence_1 = { 51 ffd5 6a0a ff15???????? 6a00 }
            // n = 5, score = 100
            //   51                   | push                ecx
            //   ffd5                 | call                ebp
            //   6a0a                 | push                0xa
            //   ff15????????         |                     
            //   6a00                 | push                0

        $sequence_2 = { 8b742454 6808020000 68???????? 6a00 8935???????? ff15???????? }
            // n = 6, score = 100
            //   8b742454             | mov                 esi, dword ptr [esp + 0x54]
            //   6808020000           | push                0x208
            //   68????????           |                     
            //   6a00                 | push                0
            //   8935????????         |                     
            //   ff15????????         |                     

        $sequence_3 = { 750c 8b44240c 8d9078ffffff eb71 b904000000 bf???????? 8bf0 }
            // n = 7, score = 100
            //   750c                 | jne                 0xe
            //   8b44240c             | mov                 eax, dword ptr [esp + 0xc]
            //   8d9078ffffff         | lea                 edx, [eax - 0x88]
            //   eb71                 | jmp                 0x73
            //   b904000000           | mov                 ecx, 4
            //   bf????????           |                     
            //   8bf0                 | mov                 esi, eax

        $sequence_4 = { 56 e8???????? 83c408 8b54241c 55 2bc6 }
            // n = 6, score = 100
            //   56                   | push                esi
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b54241c             | mov                 edx, dword ptr [esp + 0x1c]
            //   55                   | push                ebp
            //   2bc6                 | sub                 eax, esi

        $sequence_5 = { ff15???????? 8b4570 85c0 750f 8b4554 6a0c 50 }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   8b4570               | mov                 eax, dword ptr [ebp + 0x70]
            //   85c0                 | test                eax, eax
            //   750f                 | jne                 0x11
            //   8b4554               | mov                 eax, dword ptr [ebp + 0x54]
            //   6a0c                 | push                0xc
            //   50                   | push                eax

        $sequence_6 = { 85c0 7d35 8b07 8b10 }
            // n = 4, score = 100
            //   85c0                 | test                eax, eax
            //   7d35                 | jge                 0x37
            //   8b07                 | mov                 eax, dword ptr [edi]
            //   8b10                 | mov                 edx, dword ptr [eax]

        $sequence_7 = { 8bca 83e103 8d442410 50 }
            // n = 4, score = 100
            //   8bca                 | mov                 ecx, edx
            //   83e103               | and                 ecx, 3
            //   8d442410             | lea                 eax, [esp + 0x10]
            //   50                   | push                eax

        $sequence_8 = { 56 53 6a00 51 8b4c2464 2bd0 52 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   53                   | push                ebx
            //   6a00                 | push                0
            //   51                   | push                ecx
            //   8b4c2464             | mov                 ecx, dword ptr [esp + 0x64]
            //   2bd0                 | sub                 edx, eax
            //   52                   | push                edx

        $sequence_9 = { 744d 81fb05020000 7445 81fb06020000 743d 81fb07020000 }
            // n = 6, score = 100
            //   744d                 | je                  0x4f
            //   81fb05020000         | cmp                 ebx, 0x205
            //   7445                 | je                  0x47
            //   81fb06020000         | cmp                 ebx, 0x206
            //   743d                 | je                  0x3f
            //   81fb07020000         | cmp                 ebx, 0x207

    condition:
        7 of them and filesize < 221184
}