rule win_cryptowall_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-08-05"
        version = "1"
        description = "Detects win.cryptowall."
        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.cryptowall"
        malpedia_rule_date = "20220805"
        malpedia_hash = "6ec06c64bcfdbeda64eff021c766b4ce34542b71"
        malpedia_version = "20220808"
        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 = { 837d0800 7502 eb4f 6a08 6a00 8d45f8 50 }
            // n = 7, score = 2100
            //   837d0800             | cmp                 dword ptr [ebp + 8], 0
            //   7502                 | jne                 4
            //   eb4f                 | jmp                 0x51
            //   6a08                 | push                8
            //   6a00                 | push                0
            //   8d45f8               | lea                 eax, [ebp - 8]
            //   50                   | push                eax

        $sequence_1 = { c645ee7c c645ef25 c645f073 c645f17d }
            // n = 4, score = 2100
            //   c645ee7c             | mov                 byte ptr [ebp - 0x12], 0x7c
            //   c645ef25             | mov                 byte ptr [ebp - 0x11], 0x25
            //   c645f073             | mov                 byte ptr [ebp - 0x10], 0x73
            //   c645f17d             | mov                 byte ptr [ebp - 0xf], 0x7d

        $sequence_2 = { 52 e8???????? 83c408 8b0d???????? 894140 }
            // n = 5, score = 2100
            //   52                   | push                edx
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b0d????????         |                     
            //   894140               | mov                 dword ptr [ecx + 0x40], eax

        $sequence_3 = { c645f125 c645f273 c645f37d c645f400 837d1000 }
            // n = 5, score = 2100
            //   c645f125             | mov                 byte ptr [ebp - 0xf], 0x25
            //   c645f273             | mov                 byte ptr [ebp - 0xe], 0x73
            //   c645f37d             | mov                 byte ptr [ebp - 0xd], 0x7d
            //   c645f400             | mov                 byte ptr [ebp - 0xc], 0
            //   837d1000             | cmp                 dword ptr [ebp + 0x10], 0

        $sequence_4 = { 33c0 eb21 0fb74d08 83f961 7c14 }
            // n = 5, score = 2100
            //   33c0                 | xor                 eax, eax
            //   eb21                 | jmp                 0x23
            //   0fb74d08             | movzx               ecx, word ptr [ebp + 8]
            //   83f961               | cmp                 ecx, 0x61
            //   7c14                 | jl                  0x16

        $sequence_5 = { 55 8bec 51 837d0800 7441 837d0c00 }
            // n = 6, score = 2100
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   51                   | push                ecx
            //   837d0800             | cmp                 dword ptr [ebp + 8], 0
            //   7441                 | je                  0x43
            //   837d0c00             | cmp                 dword ptr [ebp + 0xc], 0

        $sequence_6 = { 7d2b 6a09 6a00 e8???????? 83c408 8bf0 83c630 }
            // n = 7, score = 2100
            //   7d2b                 | jge                 0x2d
            //   6a09                 | push                9
            //   6a00                 | push                0
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8bf0                 | mov                 esi, eax
            //   83c630               | add                 esi, 0x30

        $sequence_7 = { eb09 b801000000 85c0 7599 }
            // n = 4, score = 2100
            //   eb09                 | jmp                 0xb
            //   b801000000           | mov                 eax, 1
            //   85c0                 | test                eax, eax
            //   7599                 | jne                 0xffffff9b

        $sequence_8 = { 83ec18 53 8b450c 50 }
            // n = 4, score = 2100
            //   83ec18               | sub                 esp, 0x18
            //   53                   | push                ebx
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   50                   | push                eax

        $sequence_9 = { 68a5470b2b 6a01 6a00 e8???????? 83c40c 8b15???????? }
            // n = 6, score = 2100
            //   68a5470b2b           | push                0x2b0b47a5
            //   6a01                 | push                1
            //   6a00                 | push                0
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   8b15????????         |                     

    condition:
        7 of them and filesize < 417792
}