rule win_mewsei_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.mewsei."
        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.mewsei"
        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 = { 57 8bf0 43 8d642400 53 e8???????? 8bf8 }
            // n = 7, score = 400
            //   57                   | push                edi
            //   8bf0                 | mov                 esi, eax
            //   43                   | inc                 ebx
            //   8d642400             | lea                 esp, [esp]
            //   53                   | push                ebx
            //   e8????????           |                     
            //   8bf8                 | mov                 edi, eax

        $sequence_1 = { 8bc8 8d86c39e2600 894508 c1e810 2bf9 25ff7f0000 33d2 }
            // n = 7, score = 400
            //   8bc8                 | mov                 ecx, eax
            //   8d86c39e2600         | lea                 eax, [esi + 0x269ec3]
            //   894508               | mov                 dword ptr [ebp + 8], eax
            //   c1e810               | shr                 eax, 0x10
            //   2bf9                 | sub                 edi, ecx
            //   25ff7f0000           | and                 eax, 0x7fff
            //   33d2                 | xor                 edx, edx

        $sequence_2 = { 337dfc 037de8 8dbc1f019546fd c1cf0a 037df8 0fb65822 }
            // n = 6, score = 400
            //   337dfc               | xor                 edi, dword ptr [ebp - 4]
            //   037de8               | add                 edi, dword ptr [ebp - 0x18]
            //   8dbc1f019546fd       | lea                 edi, [edi + ebx - 0x2b96aff]
            //   c1cf0a               | ror                 edi, 0xa
            //   037df8               | add                 edi, dword ptr [ebp - 8]
            //   0fb65822             | movzx               ebx, byte ptr [eax + 0x22]

        $sequence_3 = { 8b5d08 56 57 8bf0 43 8d642400 }
            // n = 6, score = 400
            //   8b5d08               | mov                 ebx, dword ptr [ebp + 8]
            //   56                   | push                esi
            //   57                   | push                edi
            //   8bf0                 | mov                 esi, eax
            //   43                   | inc                 ebx
            //   8d642400             | lea                 esp, [esp]

        $sequence_4 = { 83c404 57 894dfc e8???????? }
            // n = 4, score = 400
            //   83c404               | add                 esp, 4
            //   57                   | push                edi
            //   894dfc               | mov                 dword ptr [ebp - 4], ecx
            //   e8????????           |                     

        $sequence_5 = { 0bfb 0fb65818 c1e708 0bfb 8b5df8 897970 897dc8 }
            // n = 7, score = 400
            //   0bfb                 | or                  edi, ebx
            //   0fb65818             | movzx               ebx, byte ptr [eax + 0x18]
            //   c1e708               | shl                 edi, 8
            //   0bfb                 | or                  edi, ebx
            //   8b5df8               | mov                 ebx, dword ptr [ebp - 8]
            //   897970               | mov                 dword ptr [ecx + 0x70], edi
            //   897dc8               | mov                 dword ptr [ebp - 0x38], edi

        $sequence_6 = { ebe6 56 8b35???????? 57 }
            // n = 4, score = 400
            //   ebe6                 | jmp                 0xffffffe8
            //   56                   | push                esi
            //   8b35????????         |                     
            //   57                   | push                edi

        $sequence_7 = { c1cf0b 03fe f7d2 0bd7 }
            // n = 4, score = 400
            //   c1cf0b               | ror                 edi, 0xb
            //   03fe                 | add                 edi, esi
            //   f7d2                 | not                 edx
            //   0bd7                 | or                  edx, edi

        $sequence_8 = { 83c410 6a06 53 ff15???????? }
            // n = 4, score = 400
            //   83c410               | add                 esp, 0x10
            //   6a06                 | push                6
            //   53                   | push                ebx
            //   ff15????????         |                     

        $sequence_9 = { c1ea10 884708 8b4610 884f05 885706 8bc8 8bd0 }
            // n = 7, score = 400
            //   c1ea10               | shr                 edx, 0x10
            //   884708               | mov                 byte ptr [edi + 8], al
            //   8b4610               | mov                 eax, dword ptr [esi + 0x10]
            //   884f05               | mov                 byte ptr [edi + 5], cl
            //   885706               | mov                 byte ptr [edi + 6], dl
            //   8bc8                 | mov                 ecx, eax
            //   8bd0                 | mov                 edx, eax

    condition:
        7 of them and filesize < 504832
}