rule win_cryptowall_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-04-08"
        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 = "20220405"
        malpedia_hash = "ecd38294bd47d5589be5cd5490dc8bb4804afc2a"
        malpedia_version = "20220411"
        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 = { 55 8bec 6804010000 e8???????? 83c404 }
            // n = 5, score = 2100
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   6804010000           | push                0x104
            //   e8????????           |                     
            //   83c404               | add                 esp, 4

        $sequence_1 = { 668955e4 b873000000 668945e6 b974000000 66894de8 ba65000000 668955ea }
            // n = 7, score = 2100
            //   668955e4             | mov                 word ptr [ebp - 0x1c], dx
            //   b873000000           | mov                 eax, 0x73
            //   668945e6             | mov                 word ptr [ebp - 0x1a], ax
            //   b974000000           | mov                 ecx, 0x74
            //   66894de8             | mov                 word ptr [ebp - 0x18], cx
            //   ba65000000           | mov                 edx, 0x65
            //   668955ea             | mov                 word ptr [ebp - 0x16], dx

        $sequence_2 = { 8b4d10 8d540902 52 8b450c 50 8b4d08 51 }
            // n = 7, score = 2100
            //   8b4d10               | mov                 ecx, dword ptr [ebp + 0x10]
            //   8d540902             | lea                 edx, dword ptr [ecx + ecx + 2]
            //   52                   | push                edx
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   50                   | push                eax
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   51                   | push                ecx

        $sequence_3 = { e8???????? 83c408 8b0d???????? 898154010000 }
            // n = 4, score = 2100
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b0d????????         |                     
            //   898154010000         | mov                 dword ptr [ecx + 0x154], eax

        $sequence_4 = { 83fa5a 7f0b 0fb74508 83c020 66894508 }
            // n = 5, score = 2100
            //   83fa5a               | cmp                 edx, 0x5a
            //   7f0b                 | jg                  0xd
            //   0fb74508             | movzx               eax, word ptr [ebp + 8]
            //   83c020               | add                 eax, 0x20
            //   66894508             | mov                 word ptr [ebp + 8], ax

        $sequence_5 = { 837d0800 7441 837d0c00 743b c745fc00000000 eb09 8b45fc }
            // n = 7, score = 2100
            //   837d0800             | cmp                 dword ptr [ebp + 8], 0
            //   7441                 | je                  0x43
            //   837d0c00             | cmp                 dword ptr [ebp + 0xc], 0
            //   743b                 | je                  0x3d
            //   c745fc00000000       | mov                 dword ptr [ebp - 4], 0
            //   eb09                 | jmp                 0xb
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]

        $sequence_6 = { 8b08 894d08 eb09 8b5508 83c202 895508 8b4508 }
            // n = 7, score = 2100
            //   8b08                 | mov                 ecx, dword ptr [eax]
            //   894d08               | mov                 dword ptr [ebp + 8], ecx
            //   eb09                 | jmp                 0xb
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   83c202               | add                 edx, 2
            //   895508               | mov                 dword ptr [ebp + 8], edx
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]

        $sequence_7 = { 8b4510 50 e8???????? 83c404 8945f8 8b4d0c }
            // n = 6, score = 2100
            //   8b4510               | mov                 eax, dword ptr [ebp + 0x10]
            //   50                   | push                eax
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   8945f8               | mov                 dword ptr [ebp - 8], eax
            //   8b4d0c               | mov                 ecx, dword ptr [ebp + 0xc]

        $sequence_8 = { 837d1400 7425 837d1000 741f }
            // n = 4, score = 2100
            //   837d1400             | cmp                 dword ptr [ebp + 0x14], 0
            //   7425                 | je                  0x27
            //   837d1000             | cmp                 dword ptr [ebp + 0x10], 0
            //   741f                 | je                  0x21

        $sequence_9 = { eb72 8b4508 50 e8???????? 83c404 }
            // n = 5, score = 2100
            //   eb72                 | jmp                 0x74
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   50                   | push                eax
            //   e8????????           |                     
            //   83c404               | add                 esp, 4

    condition:
        7 of them and filesize < 417792
}