rule win_cryptowall_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.cryptowall"
        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 = { 50 8b4dec 51 e8???????? 8b5030 }
            // n = 5, score = 2100
            //   50                   | push                eax
            //   8b4dec               | mov                 ecx, dword ptr [ebp - 0x14]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   8b5030               | mov                 edx, dword ptr [eax + 0x30]

        $sequence_1 = { 8b45fc 50 8b4dec 51 e8???????? 8b5030 }
            // n = 6, score = 2100
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   50                   | push                eax
            //   8b4dec               | mov                 ecx, dword ptr [ebp - 0x14]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   8b5030               | mov                 edx, dword ptr [eax + 0x30]

        $sequence_2 = { 8b45fc 2d00080000 8945fc ebe5 8b45fc 8be5 }
            // n = 6, score = 2100
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   2d00080000           | sub                 eax, 0x800
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   ebe5                 | jmp                 0xffffffe7
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   8be5                 | mov                 esp, ebp

        $sequence_3 = { 837d0800 750a b80d0000c0 e9???????? }
            // n = 4, score = 2100
            //   837d0800             | cmp                 dword ptr [ebp + 8], 0
            //   750a                 | jne                 0xc
            //   b80d0000c0           | mov                 eax, 0xc000000d
            //   e9????????           |                     

        $sequence_4 = { 52 e8???????? 83c408 8b0d???????? 8981b4000000 }
            // n = 5, score = 2100
            //   52                   | push                edx
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b0d????????         |                     
            //   8981b4000000         | mov                 dword ptr [ecx + 0xb4], eax

        $sequence_5 = { eb17 8b4508 ba10270000 f7e2 }
            // n = 4, score = 2100
            //   eb17                 | jmp                 0x19
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   ba10270000           | mov                 edx, 0x2710
            //   f7e2                 | mul                 edx

        $sequence_6 = { 668945ec b933000000 66894dee ba32000000 668955f0 33c0 668945f2 }
            // n = 7, score = 2100
            //   668945ec             | mov                 word ptr [ebp - 0x14], ax
            //   b933000000           | mov                 ecx, 0x33
            //   66894dee             | mov                 word ptr [ebp - 0x12], cx
            //   ba32000000           | mov                 edx, 0x32
            //   668955f0             | mov                 word ptr [ebp - 0x10], dx
            //   33c0                 | xor                 eax, eax
            //   668945f2             | mov                 word ptr [ebp - 0xe], ax

        $sequence_7 = { 83c408 3b4508 751c 837d0cff 740b }
            // n = 5, score = 2100
            //   83c408               | add                 esp, 8
            //   3b4508               | cmp                 eax, dword ptr [ebp + 8]
            //   751c                 | jne                 0x1e
            //   837d0cff             | cmp                 dword ptr [ebp + 0xc], -1
            //   740b                 | je                  0xd

        $sequence_8 = { 6a08 6a00 8d55ec 52 }
            // n = 4, score = 2100
            //   6a08                 | push                8
            //   6a00                 | push                0
            //   8d55ec               | lea                 edx, [ebp - 0x14]
            //   52                   | push                edx

        $sequence_9 = { e8???????? 83c408 8b0d???????? 8981f4000000 }
            // n = 4, score = 2100
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b0d????????         |                     
            //   8981f4000000         | mov                 dword ptr [ecx + 0xf4], eax

    condition:
        7 of them and filesize < 417792
}