rule win_wannacryptor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-08-17"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.4.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.wannacryptor"
        malpedia_rule_date = "20200817"
        malpedia_hash = "8c895fd01eccb47a6225bcb1a3ba53cbb98644c5"
        malpedia_version = "20200817"
        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 / approach 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 = { 8b442418 8b5500 25ff000000 8d4c2419 83c002 50 }
            // n = 6, score = 600
            //   8b442418             | mov                 eax, dword ptr [esp + 0x18]
            //   8b5500               | mov                 edx, dword ptr [ebp]
            //   25ff000000           | and                 eax, 0xff
            //   8d4c2419             | lea                 ecx, [esp + 0x19]
            //   83c002               | add                 eax, 2
            //   50                   | push                eax

        $sequence_1 = { 742a 85f6 7c3a 7e16 8b8b3c010000 8d442418 }
            // n = 6, score = 600
            //   742a                 | je                  0x2c
            //   85f6                 | test                esi, esi
            //   7c3a                 | jl                  0x3c
            //   7e16                 | jle                 0x18
            //   8b8b3c010000         | mov                 ecx, dword ptr [ebx + 0x13c]
            //   8d442418             | lea                 eax, [esp + 0x18]

        $sequence_2 = { 884c2412 743b 33c0 33c9 8a643e03 8a4c3e01 8a443e02 }
            // n = 7, score = 600
            //   884c2412             | mov                 byte ptr [esp + 0x12], cl
            //   743b                 | je                  0x3d
            //   33c0                 | xor                 eax, eax
            //   33c9                 | xor                 ecx, ecx
            //   8a643e03             | mov                 ah, byte ptr [esi + edi + 3]
            //   8a4c3e01             | mov                 cl, byte ptr [esi + edi + 1]
            //   8a443e02             | mov                 al, byte ptr [esi + edi + 2]

        $sequence_3 = { 6a00 53 ff15???????? 8bac2418020000 }
            // n = 4, score = 600
            //   6a00                 | push                0
            //   53                   | push                ebx
            //   ff15????????         |                     
            //   8bac2418020000       | mov                 ebp, dword ptr [esp + 0x218]

        $sequence_4 = { 6a02 8d4701 51 8bce 89442424 }
            // n = 5, score = 600
            //   6a02                 | push                2
            //   8d4701               | lea                 eax, [edi + 1]
            //   51                   | push                ecx
            //   8bce                 | mov                 ecx, esi
            //   89442424             | mov                 dword ptr [esp + 0x24], eax

        $sequence_5 = { 7d0d 8b5168 8b7960 03d7 }
            // n = 4, score = 600
            //   7d0d                 | jge                 0xf
            //   8b5168               | mov                 edx, dword ptr [ecx + 0x68]
            //   8b7960               | mov                 edi, dword ptr [ecx + 0x60]
            //   03d7                 | add                 edx, edi

        $sequence_6 = { f7f9 85c0 7443 3bf9 7c3f }
            // n = 5, score = 600
            //   f7f9                 | idiv                ecx
            //   85c0                 | test                eax, eax
            //   7443                 | je                  0x45
            //   3bf9                 | cmp                 edi, ecx
            //   7c3f                 | jl                  0x41

        $sequence_7 = { 8bc8 83e103 3bea f3a4 756f c644241c00 8d54241c }
            // n = 7, score = 600
            //   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
            //   8d54241c             | lea                 edx, [esp + 0x1c]

        $sequence_8 = { 57 837d0000 0f85d2000000 837d04ff 0f85c8000000 53 8d9d40010000 }
            // n = 7, score = 600
            //   57                   | push                edi
            //   837d0000             | cmp                 dword ptr [ebp], 0
            //   0f85d2000000         | jne                 0xd8
            //   837d04ff             | cmp                 dword ptr [ebp + 4], -1
            //   0f85c8000000         | jne                 0xce
            //   53                   | push                ebx
            //   8d9d40010000         | lea                 ebx, [ebp + 0x140]

        $sequence_9 = { c20400 8b542404 8b02 85c0 7c1d 56 }
            // n = 6, score = 600
            //   c20400               | ret                 4
            //   8b542404             | mov                 edx, dword ptr [esp + 4]
            //   8b02                 | mov                 eax, dword ptr [edx]
            //   85c0                 | test                eax, eax
            //   7c1d                 | jl                  0x1f
            //   56                   | push                esi

    condition:
        7 of them and filesize < 540672
}