rule win_nexster_bot_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        version = "1"
        description = "Detects win.nexster_bot."
        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.nexster_bot"
        malpedia_rule_date = "20230328"
        malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d"
        malpedia_version = "20230407"
        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 = { 8b0c8d20804100 83e61f c1e606 89040e 8bc3 5f 5e }
            // n = 7, score = 100
            //   8b0c8d20804100       | mov                 ecx, dword ptr [ecx*4 + 0x418020]
            //   83e61f               | and                 esi, 0x1f
            //   c1e606               | shl                 esi, 6
            //   89040e               | mov                 dword ptr [esi + ecx], eax
            //   8bc3                 | mov                 eax, ebx
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_1 = { 66898dbc050000 e8???????? 83c424 8d85bc050000 50 6804010000 }
            // n = 6, score = 100
            //   66898dbc050000       | mov                 word ptr [ebp + 0x5bc], cx
            //   e8????????           |                     
            //   83c424               | add                 esp, 0x24
            //   8d85bc050000         | lea                 eax, [ebp + 0x5bc]
            //   50                   | push                eax
            //   6804010000           | push                0x104

        $sequence_2 = { 8d542438 52 6a00 6a00 6a00 6a01 6a00 }
            // n = 7, score = 100
            //   8d542438             | lea                 edx, [esp + 0x38]
            //   52                   | push                edx
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   6a01                 | push                1
            //   6a00                 | push                0

        $sequence_3 = { 33f6 33c0 0fbe84c1b0194100 6a07 c1f804 59 }
            // n = 6, score = 100
            //   33f6                 | xor                 esi, esi
            //   33c0                 | xor                 eax, eax
            //   0fbe84c1b0194100     | movsx               eax, byte ptr [ecx + eax*8 + 0x4119b0]
            //   6a07                 | push                7
            //   c1f804               | sar                 eax, 4
            //   59                   | pop                 ecx

        $sequence_4 = { 3ac3 752d 56 6a03 8d542415 6a01 }
            // n = 6, score = 100
            //   3ac3                 | cmp                 al, bl
            //   752d                 | jne                 0x2f
            //   56                   | push                esi
            //   6a03                 | push                3
            //   8d542415             | lea                 edx, [esp + 0x15]
            //   6a01                 | push                1

        $sequence_5 = { e8???????? 8b742410 8d942494000000 8bc6 2bd6 }
            // n = 5, score = 100
            //   e8????????           |                     
            //   8b742410             | mov                 esi, dword ptr [esp + 0x10]
            //   8d942494000000       | lea                 edx, [esp + 0x94]
            //   8bc6                 | mov                 eax, esi
            //   2bd6                 | sub                 edx, esi

        $sequence_6 = { 8d0cbd20804100 8901 8305????????20 8b11 81c200080000 }
            // n = 5, score = 100
            //   8d0cbd20804100       | lea                 ecx, [edi*4 + 0x418020]
            //   8901                 | mov                 dword ptr [ecx], eax
            //   8305????????20       |                     
            //   8b11                 | mov                 edx, dword ptr [ecx]
            //   81c200080000         | add                 edx, 0x800

        $sequence_7 = { 6a00 52 8885c0140000 e8???????? }
            // n = 4, score = 100
            //   6a00                 | push                0
            //   52                   | push                edx
            //   8885c0140000         | mov                 byte ptr [ebp + 0x14c0], al
            //   e8????????           |                     

        $sequence_8 = { 83c40c 8d8dbc0f0000 8d95bc150000 8a01 8802 41 }
            // n = 6, score = 100
            //   83c40c               | add                 esp, 0xc
            //   8d8dbc0f0000         | lea                 ecx, [ebp + 0xfbc]
            //   8d95bc150000         | lea                 edx, [ebp + 0x15bc]
            //   8a01                 | mov                 al, byte ptr [ecx]
            //   8802                 | mov                 byte ptr [edx], al
            //   41                   | inc                 ecx

        $sequence_9 = { 50 ff15???????? 68ff010000 8be8 }
            // n = 4, score = 100
            //   50                   | push                eax
            //   ff15????????         |                     
            //   68ff010000           | push                0x1ff
            //   8be8                 | mov                 ebp, eax

    condition:
        7 of them and filesize < 245760
}