rule win_wannacryptor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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 = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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 = { 5d 5b 81c410040000 c21000 8bb42424040000 }
            // n = 5, score = 600
            //   5d                   | pop                 ebp
            //   5b                   | pop                 ebx
            //   81c410040000         | add                 esp, 0x410
            //   c21000               | ret                 0x10
            //   8bb42424040000       | mov                 esi, dword ptr [esp + 0x424]

        $sequence_2 = { 83c408 89442430 8d442428 8d4c2430 50 51 8954243c }
            // n = 7, score = 600
            //   83c408               | add                 esp, 8
            //   89442430             | mov                 dword ptr [esp + 0x30], eax
            //   8d442428             | lea                 eax, [esp + 0x28]
            //   8d4c2430             | lea                 ecx, [esp + 0x30]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   8954243c             | mov                 dword ptr [esp + 0x3c], edx

        $sequence_3 = { 8bce e8???????? 8a4649 84c0 7419 8b4620 }
            // n = 6, score = 600
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     
            //   8a4649               | mov                 al, byte ptr [esi + 0x49]
            //   84c0                 | test                al, al
            //   7419                 | je                  0x1b
            //   8b4620               | mov                 eax, dword ptr [esi + 0x20]

        $sequence_4 = { 33ff 85c0 7e2b 8bd8 8b5500 03cf 8a4411ff }
            // n = 7, score = 600
            //   33ff                 | xor                 edi, edi
            //   85c0                 | test                eax, eax
            //   7e2b                 | jle                 0x2d
            //   8bd8                 | mov                 ebx, eax
            //   8b5500               | mov                 edx, dword ptr [ebp]
            //   03cf                 | add                 ecx, edi
            //   8a4411ff             | mov                 al, byte ptr [ecx + edx - 1]

        $sequence_5 = { 83fa01 0f850f010000 38564b 7526 8b4644 }
            // n = 5, score = 600
            //   83fa01               | cmp                 edx, 1
            //   0f850f010000         | jne                 0x115
            //   38564b               | cmp                 byte ptr [esi + 0x4b], dl
            //   7526                 | jne                 0x28
            //   8b4644               | mov                 eax, dword ptr [esi + 0x44]

        $sequence_6 = { b907000000 33c0 8d7e08 c74604ffffffff f3ab 66ab }
            // n = 6, score = 600
            //   b907000000           | mov                 ecx, 7
            //   33c0                 | xor                 eax, eax
            //   8d7e08               | lea                 edi, [esi + 8]
            //   c74604ffffffff       | mov                 dword ptr [esi + 4], 0xffffffff
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   66ab                 | stosw               word ptr es:[edi], ax

        $sequence_7 = { e8???????? 8b0e 8bf8 8b442414 897c241c }
            // n = 5, score = 600
            //   e8????????           |                     
            //   8b0e                 | mov                 ecx, dword ptr [esi]
            //   8bf8                 | mov                 edi, eax
            //   8b442414             | mov                 eax, dword ptr [esp + 0x14]
            //   897c241c             | mov                 dword ptr [esp + 0x1c], edi

        $sequence_8 = { e8???????? 8bf8 8b4640 8d542408 8b48f8 52 51 }
            // n = 7, score = 600
            //   e8????????           |                     
            //   8bf8                 | mov                 edi, eax
            //   8b4640               | mov                 eax, dword ptr [esi + 0x40]
            //   8d542408             | lea                 edx, [esp + 8]
            //   8b48f8               | mov                 ecx, dword ptr [eax - 8]
            //   52                   | push                edx
            //   51                   | push                ecx

        $sequence_9 = { 8d4c2420 b306 50 51 }
            // n = 4, score = 600
            //   8d4c2420             | lea                 ecx, [esp + 0x20]
            //   b306                 | mov                 bl, 6
            //   50                   | push                eax
            //   51                   | push                ecx

    condition:
        7 of them and filesize < 540672
}