rule win_grillmark_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.grillmark."
        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.grillmark"
        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 = { 59 33c0 8dbdf5fcffff 8b7508 f3ab }
            // n = 5, score = 300
            //   59                   | pop                 ecx
            //   33c0                 | xor                 eax, eax
            //   8dbdf5fcffff         | lea                 edi, [ebp - 0x30b]
            //   8b7508               | mov                 esi, dword ptr [ebp + 8]
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax

        $sequence_1 = { 83c104 ebf5 5d c3 }
            // n = 4, score = 300
            //   83c104               | add                 ecx, 4
            //   ebf5                 | jmp                 0xfffffff7
            //   5d                   | pop                 ebp
            //   c3                   | ret                 

        $sequence_2 = { 8065ff00 eb6c ff45f8 880f 47 eb64 80f909 }
            // n = 7, score = 300
            //   8065ff00             | and                 byte ptr [ebp - 1], 0
            //   eb6c                 | jmp                 0x6e
            //   ff45f8               | inc                 dword ptr [ebp - 8]
            //   880f                 | mov                 byte ptr [edi], cl
            //   47                   | inc                 edi
            //   eb64                 | jmp                 0x66
            //   80f909               | cmp                 cl, 9

        $sequence_3 = { 8911 8d1406 83c104 3b5510 72d7 5f 5e }
            // n = 7, score = 300
            //   8911                 | mov                 dword ptr [ecx], edx
            //   8d1406               | lea                 edx, [esi + eax]
            //   83c104               | add                 ecx, 4
            //   3b5510               | cmp                 edx, dword ptr [ebp + 0x10]
            //   72d7                 | jb                  0xffffffd9
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_4 = { 53 50 8d45c8 50 6a13 }
            // n = 5, score = 300
            //   53                   | push                ebx
            //   50                   | push                eax
            //   8d45c8               | lea                 eax, [ebp - 0x38]
            //   50                   | push                eax
            //   6a13                 | push                0x13

        $sequence_5 = { 7473 8d45c8 50 e8???????? 3d94010000 }
            // n = 5, score = 300
            //   7473                 | je                  0x75
            //   8d45c8               | lea                 eax, [ebp - 0x38]
            //   50                   | push                eax
            //   e8????????           |                     
            //   3d94010000           | cmp                 eax, 0x194

        $sequence_6 = { 8945fc 0f84b8000000 56 e8???????? }
            // n = 4, score = 300
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   0f84b8000000         | je                  0xbe
            //   56                   | push                esi
            //   e8????????           |                     

        $sequence_7 = { 33c0 8d7dc9 885dc8 895df4 f3ab 66ab }
            // n = 6, score = 300
            //   33c0                 | xor                 eax, eax
            //   8d7dc9               | lea                 edi, [ebp - 0x37]
            //   885dc8               | mov                 byte ptr [ebp - 0x38], bl
            //   895df4               | mov                 dword ptr [ebp - 0xc], ebx
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   66ab                 | stosw               word ptr es:[edi], ax

        $sequence_8 = { 50 57 ffb604010000 56 e8???????? 83c410 85c0 }
            // n = 7, score = 300
            //   50                   | push                eax
            //   57                   | push                edi
            //   ffb604010000         | push                dword ptr [esi + 0x104]
            //   56                   | push                esi
            //   e8????????           |                     
            //   83c410               | add                 esp, 0x10
            //   85c0                 | test                eax, eax

        $sequence_9 = { 0a450f 46 8806 8b45fc 46 3b45f4 0f82d6feffff }
            // n = 7, score = 300
            //   0a450f               | or                  al, byte ptr [ebp + 0xf]
            //   46                   | inc                 esi
            //   8806                 | mov                 byte ptr [esi], al
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   46                   | inc                 esi
            //   3b45f4               | cmp                 eax, dword ptr [ebp - 0xc]
            //   0f82d6feffff         | jb                  0xfffffedc

    condition:
        7 of them and filesize < 212992
}