rule win_grapeloader_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.grapeloader."
        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.grapeloader"
        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 = { e8???????? 488985c0000000 eb00 488d8d9f030000 }
            // n = 4, score = 100
            //   e8????????           |                     
            //   488985c0000000       | movzx               ecx, word ptr [esp + 0x34]
            //   eb00                 | movsx               eax, word ptr [esp + 0x5c]
            //   488d8d9f030000       | imul                eax, dword ptr [esp + 0x3c], 0x4c54

        $sequence_1 = { 4883ec28 48894c2420 488b4c2420 4883c108 31d2 e8???????? 90 }
            // n = 7, score = 100
            //   4883ec28             | movzx               eax, byte ptr [esp + 0x2e]
            //   48894c2420           | imul                eax, ecx
            //   488b4c2420           | mov                 byte ptr [esp + 0x2e], al
            //   4883c108             | mov                 byte ptr [esp + 0x23], 0xa6
            //   31d2                 | movzx               eax, byte ptr [esp + 0x2f]
            //   e8????????           |                     
            //   90                   | mov                 ecx, dword ptr [esp + 0x24]

        $sequence_2 = { 0fbf442432 0fafc1 6689442432 0fb74c242c 0fbf442432 29c8 6689442432 }
            // n = 7, score = 100
            //   0fbf442432           | mov                 al, byte ptr [esp + 0x1b]
            //   0fafc1               | add                 al, 1
            //   6689442432           | mov                 byte ptr [esp + 0x23], al
            //   0fb74c242c           | mov                 ecx, dword ptr [esp + 0x1c]
            //   0fbf442432           | movsx               eax, byte ptr [esp + 0x23]
            //   29c8                 | add                 eax, ecx
            //   6689442432           | mov                 byte ptr [esp + 0x23], al

        $sequence_3 = { 7429 488d1551cc0000 ff15???????? 4885c0 7412 49ba707b5a5e9b8701a2 }
            // n = 6, score = 100
            //   7429                 | dec                 esp
            //   488d1551cc0000       | lea                 eax, [0xb61e]
            //   ff15????????         |                     
            //   4885c0               | dec                 eax
            //   7412                 | mov                 edi, ecx
            //   49ba707b5a5e9b8701a2     | dec    eax

        $sequence_4 = { 0fb744243c 0fafc1 668944243c 0fbe442421 6bc0b9 88442421 }
            // n = 6, score = 100
            //   0fb744243c           | movsx               eax, byte ptr [esp + 0x37]
            //   0fafc1               | imul                eax, ecx
            //   668944243c           | imul                eax, dword ptr [esp + 0x38], 0x8336f372
            //   0fbe442421           | mov                 dword ptr [esp + 0x38], eax
            //   6bc0b9               | mov                 ecx, dword ptr [esp + 0x14]
            //   88442421             | movsx               eax, word ptr [esp + 0x36]

        $sequence_5 = { 4883ec18 4889542410 48894c2408 48c7042400000000 48833c242e 7328 488b442410 }
            // n = 7, score = 100
            //   4883ec18             | mov                 dword ptr [esp + 0x4c], eax
            //   4889542410           | movzx               eax, word ptr [esp + 0x52]
            //   48894c2408           | add                 eax, 0xef
            //   48c7042400000000     | mov                 word ptr [esp + 0x52], ax
            //   48833c242e           | mov                 eax, dword ptr [esp + 0x4c]
            //   7328                 | sub                 eax, ecx
            //   488b442410           | mov                 dword ptr [esp + 0x4c], eax

        $sequence_6 = { 488d95d8010000 488955d0 e8???????? 488b4dd0 e8???????? 488945d8 eb00 }
            // n = 7, score = 100
            //   488d95d8010000       | mov                 dword ptr [esp + 0x64], eax
            //   488955d0             | movsx               eax, word ptr [esp + 0x60]
            //   e8????????           |                     
            //   488b4dd0             | sub                 eax, 0x98
            //   e8????????           |                     
            //   488945d8             | imul                eax, ecx
            //   eb00                 | mov                 byte ptr [esp + 0x62], al

        $sequence_7 = { 4431c2 881408 8a442427 0401 88442427 ebaa }
            // n = 6, score = 100
            //   4431c2               | mov                 word ptr [esp + 0x32], ax
            //   881408               | movzx               ecx, word ptr [esp + 0x32]
            //   8a442427             | mov                 ecx, dword ptr [esp + 0x2c]
            //   0401                 | movsx               eax, byte ptr [esp + 0x35]
            //   88442427             | sub                 eax, ecx
            //   ebaa                 | mov                 byte ptr [esp + 0x35], al

        $sequence_8 = { 8b442454 0faf44241c 8944241c 66c7442402fcda 0fbe442453 69c05cdd0000 88442453 }
            // n = 7, score = 100
            //   8b442454             | cmp                 dword ptr [esp + 0x28], 0xa
            //   0faf44241c           | jae                 0x1d5
            //   8944241c             | mov                 byte ptr [esp + 0x27], 0
            //   66c7442402fcda       | movzx               eax, byte ptr [esp + 0x27]
            //   0fbe442453           | dec                 eax
            //   69c05cdd0000         | cmp                 eax, 1
            //   88442453             | dec                 eax

        $sequence_9 = { 66c744241a4ba9 0fbf44241a 3d6e91ffff 0f8d95000000 8b442420 05c8e8005e 89442420 }
            // n = 7, score = 100
            //   66c744241a4ba9       | movzx               eax, byte ptr [esp + 0x62]
            //   0fbf44241a           | add                 eax, ecx
            //   3d6e91ffff           | movsx               eax, word ptr [esp + 4]
            //   0f8d95000000         | imul                eax, dword ptr [esp + 0x3c]
            //   8b442420             | mov                 dword ptr [esp + 0x3c], eax
            //   05c8e8005e           | imul                eax, dword ptr [esp + 0x28], 0x96
            //   89442420             | mov                 dword ptr [esp + 0x28], eax

    condition:
        7 of them and filesize < 397312
}