rule win_fct_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.fct."
        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.fct"
        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 = { 3bc8 772f 83fb08 8d0409 50 8d75d8 0f4375d8 }
            // n = 7, score = 100
            //   3bc8                 | cmp                 ecx, eax
            //   772f                 | ja                  0x31
            //   83fb08               | cmp                 ebx, 8
            //   8d0409               | lea                 eax, [ecx + ecx]
            //   50                   | push                eax
            //   8d75d8               | lea                 esi, [ebp - 0x28]
            //   0f4375d8             | cmovae              esi, dword ptr [ebp - 0x28]

        $sequence_1 = { 8b8d74fdffff ebdb 57 ff15???????? c645fc04 33c0 }
            // n = 6, score = 100
            //   8b8d74fdffff         | mov                 ecx, dword ptr [ebp - 0x28c]
            //   ebdb                 | jmp                 0xffffffdd
            //   57                   | push                edi
            //   ff15????????         |                     
            //   c645fc04             | mov                 byte ptr [ebp - 4], 4
            //   33c0                 | xor                 eax, eax

        $sequence_2 = { c745ec8e2d4000 894df8 8945fc 64a100000000 8945e8 8d45e8 64a300000000 }
            // n = 7, score = 100
            //   c745ec8e2d4000       | mov                 dword ptr [ebp - 0x14], 0x402d8e
            //   894df8               | mov                 dword ptr [ebp - 8], ecx
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   64a100000000         | mov                 eax, dword ptr fs:[0]
            //   8945e8               | mov                 dword ptr [ebp - 0x18], eax
            //   8d45e8               | lea                 eax, [ebp - 0x18]
            //   64a300000000         | mov                 dword ptr fs:[0], eax

        $sequence_3 = { 50 8d45f4 64a300000000 8bf9 89bd0cfdffff 33c0 8d5102 }
            // n = 7, score = 100
            //   50                   | push                eax
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   64a300000000         | mov                 dword ptr fs:[0], eax
            //   8bf9                 | mov                 edi, ecx
            //   89bd0cfdffff         | mov                 dword ptr [ebp - 0x2f4], edi
            //   33c0                 | xor                 eax, eax
            //   8d5102               | lea                 edx, [ecx + 2]

        $sequence_4 = { 0f8495330000 c3 833d????????ff 7503 33c0 c3 53 }
            // n = 7, score = 100
            //   0f8495330000         | je                  0x339b
            //   c3                   | ret                 
            //   833d????????ff       |                     
            //   7503                 | jne                 5
            //   33c0                 | xor                 eax, eax
            //   c3                   | ret                 
            //   53                   | push                ebx

        $sequence_5 = { 0f8421010000 6683bd80fdffff2e 0f84cf040000 8bcf c745e800000000 33c0 c745ec07000000 }
            // n = 7, score = 100
            //   0f8421010000         | je                  0x127
            //   6683bd80fdffff2e     | cmp                 word ptr [ebp - 0x280], 0x2e
            //   0f84cf040000         | je                  0x4d5
            //   8bcf                 | mov                 ecx, edi
            //   c745e800000000       | mov                 dword ptr [ebp - 0x18], 0
            //   33c0                 | xor                 eax, eax
            //   c745ec07000000       | mov                 dword ptr [ebp - 0x14], 7

        $sequence_6 = { 83c40c 33c0 6689047e eb21 6a04 68???????? c68510fdffff00 }
            // n = 7, score = 100
            //   83c40c               | add                 esp, 0xc
            //   33c0                 | xor                 eax, eax
            //   6689047e             | mov                 word ptr [esi + edi*2], ax
            //   eb21                 | jmp                 0x23
            //   6a04                 | push                4
            //   68????????           |                     
            //   c68510fdffff00       | mov                 byte ptr [ebp - 0x2f0], 0

        $sequence_7 = { 8b9574fdffff 2b75d4 75dd 33c9 }
            // n = 4, score = 100
            //   8b9574fdffff         | mov                 edx, dword ptr [ebp - 0x28c]
            //   2b75d4               | sub                 esi, dword ptr [ebp - 0x2c]
            //   75dd                 | jne                 0xffffffdf
            //   33c9                 | xor                 ecx, ecx

        $sequence_8 = { 51 57 8d4dbc e8???????? c745fc00000000 8b75d0 8bc6 }
            // n = 7, score = 100
            //   51                   | push                ecx
            //   57                   | push                edi
            //   8d4dbc               | lea                 ecx, [ebp - 0x44]
            //   e8????????           |                     
            //   c745fc00000000       | mov                 dword ptr [ebp - 4], 0
            //   8b75d0               | mov                 esi, dword ptr [ebp - 0x30]
            //   8bc6                 | mov                 eax, esi

        $sequence_9 = { 66890437 eb1b 50 51 }
            // n = 4, score = 100
            //   66890437             | mov                 word ptr [edi + esi], ax
            //   eb1b                 | jmp                 0x1d
            //   50                   | push                eax
            //   51                   | push                ecx

    condition:
        7 of them and filesize < 204800
}