rule win_sepsys_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.sepsys."
        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.sepsys"
        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 = { eb43 488b442430 488b4c2470 488908 488b442430 8b4c2478 894808 }
            // n = 7, score = 400
            //   eb43                 | dec                 eax
            //   488b442430           | sub                 esp, 0x118
            //   488b4c2470           | dec                 eax
            //   488908               | mov                 dword ptr [esp + 0x40], edx
            //   488b442430           | inc                 esp
            //   8b4c2478             | movzx               esp, word ptr [ecx]
            //   894808               | inc                 esp

        $sequence_1 = { c744244000000800 eb23 837c244001 7d0a c744244000400000 eb12 817c244000040000 }
            // n = 7, score = 400
            //   c744244000000800     | mov                 byte ptr [ebp + 0x4e7], 0
            //   eb23                 | dec                 eax
            //   837c244001           | mov                 eax, dword ptr [ebp + 0x3d0]
            //   7d0a                 | dec                 eax
            //   c744244000400000     | mov                 dword ptr [ebp + 0x450], eax
            //   eb12                 | movups              xmm0, xmmword ptr [ebp + 0x3c0]
            //   817c244000040000     | dec                 eax

        $sequence_2 = { c645f701 488b4110 488945e0 0f1001 0f2945d0 488b4dc8 e8???????? }
            // n = 7, score = 400
            //   c645f701             | lea                 ecx, [ebp + 0x938]
            //   488b4110             | dec                 eax
            //   488945e0             | lea                 ecx, [ebp + 0xde8]
            //   0f1001               | dec                 eax
            //   0f2945d0             | lea                 ecx, [ebp + 0xe00]
            //   488b4dc8             | jmp                 0xb22
            //   e8????????           |                     

        $sequence_3 = { e8???????? 89442420 837c242000 7406 8b442420 eb0c eb08 }
            // n = 7, score = 400
            //   e8????????           |                     
            //   89442420             | dec                 eax
            //   837c242000           | mov                 eax, dword ptr [esp + 0x60]
            //   7406                 | dec                 eax
            //   8b442420             | add                 eax, 0x15f0
            //   eb0c                 | dec                 eax
            //   eb08                 | mov                 dword ptr [esp + 0x38], eax

        $sequence_4 = { eb00 e8???????? 8845e0 eb00 488b45f8 8a4def 8808 }
            // n = 7, score = 400
            //   eb00                 | mov                 ecx, edx
            //   e8????????           |                     
            //   8845e0               | dec                 esp
            //   eb00                 | mov                 edx, eax
            //   488b45f8             | dec                 eax
            //   8a4def               | mov                 dword ptr [ebp + 0x3e8], eax
            //   8808                 | dec                 eax

        $sequence_5 = { e8???????? 4889942418010000 4889842410010000 488b842410010000 4885c0 0f95c1 0fb6d1 }
            // n = 7, score = 400
            //   e8????????           |                     
            //   4889942418010000     | dec                 eax
            //   4889842410010000     | mov                 dword ptr [esp + 0xb0], 0
            //   488b842410010000     | mov                 dword ptr [esp + 0x90], 0
            //   4885c0               | inc                 ecx
            //   0f95c1               | mov                 eax, 2
            //   0fb6d1               | xor                 edx, edx

        $sequence_6 = { e8???????? eb54 48837c246000 7421 488b442460 488b8c2488000000 48894828 }
            // n = 7, score = 400
            //   e8????????           |                     
            //   eb54                 | mov                 ecx, esi
            //   48837c246000         | inc                 ebp
            //   7421                 | xor                 ebx, ebx
            //   488b442460           | dec                 ebp
            //   488b8c2488000000     | test                ecx, ecx
            //   48894828             | inc                 ecx

        $sequence_7 = { e8???????? 488945b8 eb00 488b4db8 e8???????? 488945b0 eb00 }
            // n = 7, score = 400
            //   e8????????           |                     
            //   488945b8             | dec                 eax
            //   eb00                 | mov                 dword ptr [eax + 0xf30], 0
            //   488b4db8             | xor                 eax, eax
            //   e8????????           |                     
            //   488945b0             | test                eax, eax
            //   eb00                 | jne                 0xf84

        $sequence_8 = { 8b442420 25ff000000 8bc8 e8???????? b901000000 486bc902 488b542460 }
            // n = 7, score = 400
            //   8b442420             | jne                 0x1512
            //   25ff000000           | mov                 eax, 8
            //   8bc8                 | dec                 eax
            //   e8????????           |                     
            //   b901000000           | imul                eax, eax, 0
            //   486bc902             | dec                 eax
            //   488b542460           | lea                 ecx, [0x80a12]

        $sequence_9 = { eb08 c744246401000000 0fb6442464 88442420 0fb6442420 85c0 7415 }
            // n = 7, score = 400
            //   eb08                 | dec                 esp
            //   c744246401000000     | lea                 eax, [0xa8f0]
            //   0fb6442464           | dec                 esp
            //   88442420             | add                 eax, edx
            //   0fb6442420           | dec                 ecx
            //   85c0                 | mov                 edx, eax
            //   7415                 | inc                 esp

    condition:
        7 of them and filesize < 4538368
}