rule win_wannacryptor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        version = "1"
        description = "Detects win.wannacryptor."
        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.wannacryptor"
        malpedia_rule_date = "20230328"
        malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d"
        malpedia_version = "20230407"
        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 = { 83ec1c 56 8bf1 8a465a 84c0 756f 8a4658 }
            // n = 7, score = 600
            //   83ec1c               | sub                 esp, 0x1c
            //   56                   | push                esi
            //   8bf1                 | mov                 esi, ecx
            //   8a465a               | mov                 al, byte ptr [esi + 0x5a]
            //   84c0                 | test                al, al
            //   756f                 | jne                 0x71
            //   8a4658               | mov                 al, byte ptr [esi + 0x58]

        $sequence_1 = { c20c00 8bce e8???????? 84c0 }
            // n = 4, score = 600
            //   c20c00               | ret                 0xc
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     
            //   84c0                 | test                al, al

        $sequence_2 = { 7413 3c2f 7404 3c5c 7503 8d6e01 8a4601 }
            // n = 7, score = 600
            //   7413                 | je                  0x15
            //   3c2f                 | cmp                 al, 0x2f
            //   7404                 | je                  6
            //   3c5c                 | cmp                 al, 0x5c
            //   7503                 | jne                 5
            //   8d6e01               | lea                 ebp, [esi + 1]
            //   8a4601               | mov                 al, byte ptr [esi + 1]

        $sequence_3 = { 8b7c241c 85ff 7409 57 e8???????? 83c404 8b442420 }
            // n = 7, score = 600
            //   8b7c241c             | mov                 edi, dword ptr [esp + 0x1c]
            //   85ff                 | test                edi, edi
            //   7409                 | je                  0xb
            //   57                   | push                edi
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   8b442420             | mov                 eax, dword ptr [esp + 0x20]

        $sequence_4 = { b907000000 f3a5 66a5 a4 5f }
            // n = 5, score = 600
            //   b907000000           | mov                 ecx, 7
            //   f3a5                 | rep movsd           dword ptr es:[edi], dword ptr [esi]
            //   66a5                 | movsw               word ptr es:[edi], word ptr [esi]
            //   a4                   | movsb               byte ptr es:[edi], byte ptr [esi]
            //   5f                   | pop                 edi

        $sequence_5 = { 8975dc 83feff 750a 50 8d55f0 52 }
            // n = 6, score = 600
            //   8975dc               | mov                 dword ptr [ebp - 0x24], esi
            //   83feff               | cmp                 esi, -1
            //   750a                 | jne                 0xc
            //   50                   | push                eax
            //   8d55f0               | lea                 edx, [ebp - 0x10]
            //   52                   | push                edx

        $sequence_6 = { 83e103 f3a4 8b8c2424010000 8bd1 c1fa08 }
            // n = 5, score = 600
            //   83e103               | and                 ecx, 3
            //   f3a4                 | rep movsb           byte ptr es:[edi], byte ptr [esi]
            //   8b8c2424010000       | mov                 ecx, dword ptr [esp + 0x124]
            //   8bd1                 | mov                 edx, ecx
            //   c1fa08               | sar                 edx, 8

        $sequence_7 = { 8bf8 83c9ff 33c0 f2ae f7d1 2bf9 8bc3 }
            // n = 7, score = 600
            //   8bf8                 | mov                 edi, eax
            //   83c9ff               | or                  ecx, 0xffffffff
            //   33c0                 | xor                 eax, eax
            //   f2ae                 | repne scasb         al, byte ptr es:[edi]
            //   f7d1                 | not                 ecx
            //   2bf9                 | sub                 edi, ecx
            //   8bc3                 | mov                 eax, ebx

        $sequence_8 = { 57 8bbc2460030000 8bd9 83ff03 7424 83ff02 }
            // n = 6, score = 600
            //   57                   | push                edi
            //   8bbc2460030000       | mov                 edi, dword ptr [esp + 0x360]
            //   8bd9                 | mov                 ebx, ecx
            //   83ff03               | cmp                 edi, 3
            //   7424                 | je                  0x26
            //   83ff02               | cmp                 edi, 2

        $sequence_9 = { c744244817406700 894c244c 896c2450 89542454 e8???????? 8b5658 8b4008 }
            // n = 7, score = 600
            //   c744244817406700     | mov                 dword ptr [esp + 0x48], 0x674017
            //   894c244c             | mov                 dword ptr [esp + 0x4c], ecx
            //   896c2450             | mov                 dword ptr [esp + 0x50], ebp
            //   89542454             | mov                 dword ptr [esp + 0x54], edx
            //   e8????????           |                     
            //   8b5658               | mov                 edx, dword ptr [esi + 0x58]
            //   8b4008               | mov                 eax, dword ptr [eax + 8]

    condition:
        7 of them and filesize < 540672
}