rule win_wannacryptor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2021-06-10"
        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 = "20210604"
        malpedia_hash = "be09d5d71e77373c0f538068be31a2ad4c69cfbd"
        malpedia_version = "20210616"
        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 = { c744244817406700 894c244c 896c2450 89542454 }
            // n = 4, 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

        $sequence_1 = { 8b4d08 8b442420 83c404 49 3bf8 894d08 75a7 }
            // n = 7, score = 600
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   8b442420             | mov                 eax, dword ptr [esp + 0x20]
            //   83c404               | add                 esp, 4
            //   49                   | dec                 ecx
            //   3bf8                 | cmp                 edi, eax
            //   894d08               | mov                 dword ptr [ebp + 8], ecx
            //   75a7                 | jne                 0xffffffa9

        $sequence_2 = { 83f801 7e25 39442410 7434 8b5664 8b5e6c 8b4c2414 }
            // n = 7, score = 600
            //   83f801               | cmp                 eax, 1
            //   7e25                 | jle                 0x27
            //   39442410             | cmp                 dword ptr [esp + 0x10], eax
            //   7434                 | je                  0x36
            //   8b5664               | mov                 edx, dword ptr [esi + 0x64]
            //   8b5e6c               | mov                 ebx, dword ptr [esi + 0x6c]
            //   8b4c2414             | mov                 ecx, dword ptr [esp + 0x14]

        $sequence_3 = { 8bcb 57 e8???????? eb0d }
            // n = 4, score = 600
            //   8bcb                 | mov                 ecx, ebx
            //   57                   | push                edi
            //   e8????????           |                     
            //   eb0d                 | jmp                 0xf

        $sequence_4 = { 83d8ff 85c0 741a 33c9 8b442414 8a4c3e02 }
            // n = 6, score = 600
            //   83d8ff               | sbb                 eax, -1
            //   85c0                 | test                eax, eax
            //   741a                 | je                  0x1c
            //   33c9                 | xor                 ecx, ecx
            //   8b442414             | mov                 eax, dword ptr [esp + 0x14]
            //   8a4c3e02             | mov                 cl, byte ptr [esi + edi + 2]

        $sequence_5 = { 8b5500 03cf 8a0417 50 51 }
            // n = 5, score = 600
            //   8b5500               | mov                 edx, dword ptr [ebp]
            //   03cf                 | add                 ecx, edi
            //   8a0417               | mov                 al, byte ptr [edi + edx]
            //   50                   | push                eax
            //   51                   | push                ecx

        $sequence_6 = { e8???????? 83c404 8b03 c74304ffffffff }
            // n = 4, score = 600
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   8b03                 | mov                 eax, dword ptr [ebx]
            //   c74304ffffffff       | mov                 dword ptr [ebx + 4], 0xffffffff

        $sequence_7 = { 6a01 51 8a02 8bcf 88442418 e8???????? 8b542410 }
            // n = 7, score = 600
            //   6a01                 | push                1
            //   51                   | push                ecx
            //   8a02                 | mov                 al, byte ptr [edx]
            //   8bcf                 | mov                 ecx, edi
            //   88442418             | mov                 byte ptr [esp + 0x18], al
            //   e8????????           |                     
            //   8b542410             | mov                 edx, dword ptr [esp + 0x10]

        $sequence_8 = { f3a5 8bc8 83e103 3bea f3a4 756f c644241c00 }
            // n = 7, score = 600
            //   f3a5                 | rep movsd           dword ptr es:[edi], dword ptr [esi]
            //   8bc8                 | mov                 ecx, eax
            //   83e103               | and                 ecx, 3
            //   3bea                 | cmp                 ebp, edx
            //   f3a4                 | rep movsb           byte ptr es:[edi], byte ptr [esi]
            //   756f                 | jne                 0x71
            //   c644241c00           | mov                 byte ptr [esp + 0x1c], 0

        $sequence_9 = { 8b442414 81e1ffff0000 6a01 51 50 8bce e8???????? }
            // n = 7, score = 600
            //   8b442414             | mov                 eax, dword ptr [esp + 0x14]
            //   81e1ffff0000         | and                 ecx, 0xffff
            //   6a01                 | push                1
            //   51                   | push                ecx
            //   50                   | push                eax
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     

    condition:
        7 of them and filesize < 540672
}