rule win_classfon_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.classfon."
        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.classfon"
        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 = { f3ab 66ab 6804010000 8d4c241c }
            // n = 4, score = 200
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   66ab                 | stosw               word ptr es:[edi], ax
            //   6804010000           | push                0x104
            //   8d4c241c             | lea                 ecx, [esp + 0x1c]

        $sequence_1 = { e8???????? a1???????? 83c410 682b010000 }
            // n = 4, score = 200
            //   e8????????           |                     
            //   a1????????           |                     
            //   83c410               | add                 esp, 0x10
            //   682b010000           | push                0x12b

        $sequence_2 = { 52 57 ffd6 8b742418 8b4b54 }
            // n = 5, score = 200
            //   52                   | push                edx
            //   57                   | push                edi
            //   ffd6                 | call                esi
            //   8b742418             | mov                 esi, dword ptr [esp + 0x18]
            //   8b4b54               | mov                 ecx, dword ptr [ebx + 0x54]

        $sequence_3 = { 6800010000 8d842450030000 52 50 }
            // n = 4, score = 200
            //   6800010000           | push                0x100
            //   8d842450030000       | lea                 eax, [esp + 0x350]
            //   52                   | push                edx
            //   50                   | push                eax

        $sequence_4 = { 7429 03c6 85c0 740b 6a00 6a01 56 }
            // n = 7, score = 200
            //   7429                 | je                  0x2b
            //   03c6                 | add                 eax, esi
            //   85c0                 | test                eax, eax
            //   740b                 | je                  0xd
            //   6a00                 | push                0
            //   6a01                 | push                1
            //   56                   | push                esi

        $sequence_5 = { 33c0 8dbc244d040000 889c244c040000 f3ab 66ab aa 8d84241c010000 }
            // n = 7, score = 200
            //   33c0                 | xor                 eax, eax
            //   8dbc244d040000       | lea                 edi, [esp + 0x44d]
            //   889c244c040000       | mov                 byte ptr [esp + 0x44c], bl
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   66ab                 | stosw               word ptr es:[edi], ax
            //   aa                   | stosb               byte ptr es:[edi], al
            //   8d84241c010000       | lea                 eax, [esp + 0x11c]

        $sequence_6 = { 6a04 52 ff15???????? 898608020000 5f b801000000 }
            // n = 6, score = 200
            //   6a04                 | push                4
            //   52                   | push                edx
            //   ff15????????         |                     
            //   898608020000         | mov                 dword ptr [esi + 0x208], eax
            //   5f                   | pop                 edi
            //   b801000000           | mov                 eax, 1

        $sequence_7 = { 897d04 89450c 894508 894510 8b4b50 }
            // n = 5, score = 200
            //   897d04               | mov                 dword ptr [ebp + 4], edi
            //   89450c               | mov                 dword ptr [ebp + 0xc], eax
            //   894508               | mov                 dword ptr [ebp + 8], eax
            //   894510               | mov                 dword ptr [ebp + 0x10], eax
            //   8b4b50               | mov                 ecx, dword ptr [ebx + 0x50]

        $sequence_8 = { 6a04 e8???????? 8b8424f0070000 83c418 83f801 7e16 }
            // n = 6, score = 200
            //   6a04                 | push                4
            //   e8????????           |                     
            //   8b8424f0070000       | mov                 eax, dword ptr [esp + 0x7f0]
            //   83c418               | add                 esp, 0x18
            //   83f801               | cmp                 eax, 1
            //   7e16                 | jle                 0x18

        $sequence_9 = { 68???????? 6802000080 c744242402000080 896c242c }
            // n = 4, score = 200
            //   68????????           |                     
            //   6802000080           | push                0x80000002
            //   c744242402000080     | mov                 dword ptr [esp + 0x24], 0x80000002
            //   896c242c             | mov                 dword ptr [esp + 0x2c], ebp

    condition:
        7 of them and filesize < 73728
}