rule win_ransomexx_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2021-06-10"
        version = "1"
        description = "Detects win.ransomexx."
        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.ransomexx"
        malpedia_rule_date = "20210604"
        malpedia_hash = "be09d5d71e77373c0f538068be31a2ad4c69cfbd"
        malpedia_version = "20210616"
        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 = { 8bcf 895dfc 8955f4 e8???????? 85c0 7975 895dfc }
            // n = 7, score = 100
            //   8bcf                 | mov                 ecx, edi
            //   895dfc               | mov                 dword ptr [ebp - 4], ebx
            //   8955f4               | mov                 dword ptr [ebp - 0xc], edx
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   7975                 | jns                 0x77
            //   895dfc               | mov                 dword ptr [ebp - 4], ebx

        $sequence_1 = { 2bfe 8945fc 83ff40 721f 8b4508 53 e8???????? }
            // n = 7, score = 100
            //   2bfe                 | sub                 edi, esi
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   83ff40               | cmp                 edi, 0x40
            //   721f                 | jb                  0x21
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   53                   | push                ebx
            //   e8????????           |                     

        $sequence_2 = { 7410 817df8f0070000 7507 56 ff15???????? 5b 56 }
            // n = 7, score = 100
            //   7410                 | je                  0x12
            //   817df8f0070000       | cmp                 dword ptr [ebp - 8], 0x7f0
            //   7507                 | jne                 9
            //   56                   | push                esi
            //   ff15????????         |                     
            //   5b                   | pop                 ebx
            //   56                   | push                esi

        $sequence_3 = { 6a00 33ff 8d442474 e8???????? 83c404 85c0 0f8535020000 }
            // n = 7, score = 100
            //   6a00                 | push                0
            //   33ff                 | xor                 edi, edi
            //   8d442474             | lea                 eax, dword ptr [esp + 0x74]
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   85c0                 | test                eax, eax
            //   0f8535020000         | jne                 0x23b

        $sequence_4 = { 884736 c1ea10 0fb65640 885737 0fb6464f 884738 c1e908 }
            // n = 7, score = 100
            //   884736               | mov                 byte ptr [edi + 0x36], al
            //   c1ea10               | shr                 edx, 0x10
            //   0fb65640             | movzx               edx, byte ptr [esi + 0x40]
            //   885737               | mov                 byte ptr [edi + 0x37], dl
            //   0fb6464f             | movzx               eax, byte ptr [esi + 0x4f]
            //   884738               | mov                 byte ptr [edi + 0x38], al
            //   c1e908               | shr                 ecx, 8

        $sequence_5 = { f30f7f0a f30f6f4210 f30f6f8ab0000000 660f38dbc0 660f38dbc9 f30f7f82b0000000 }
            // n = 6, score = 100
            //   f30f7f0a             | movdqu              xmmword ptr [edx], xmm1
            //   f30f6f4210           | movdqu              xmm0, xmmword ptr [edx + 0x10]
            //   f30f6f8ab0000000     | movdqu              xmm1, xmmword ptr [edx + 0xb0]
            //   660f38dbc0           | aesimc              xmm0, xmm0
            //   660f38dbc9           | aesimc              xmm1, xmm1
            //   f30f7f82b0000000     | movdqu              xmmword ptr [edx + 0xb0], xmm0

        $sequence_6 = { 6a00 ff15???????? 8b1d???????? 57 6a00 6a01 }
            // n = 6, score = 100
            //   6a00                 | push                0
            //   ff15????????         |                     
            //   8b1d????????         |                     
            //   57                   | push                edi
            //   6a00                 | push                0
            //   6a01                 | push                1

        $sequence_7 = { 8b4df8 40 49 8945fc }
            // n = 4, score = 100
            //   8b4df8               | mov                 ecx, dword ptr [ebp - 8]
            //   40                   | inc                 eax
            //   49                   | dec                 ecx
            //   8945fc               | mov                 dword ptr [ebp - 4], eax

        $sequence_8 = { 897c2418 75a4 8db42460020000 8d5c2470 e8???????? 8bf0 }
            // n = 6, score = 100
            //   897c2418             | mov                 dword ptr [esp + 0x18], edi
            //   75a4                 | jne                 0xffffffa6
            //   8db42460020000       | lea                 esi, dword ptr [esp + 0x260]
            //   8d5c2470             | lea                 ebx, dword ptr [esp + 0x70]
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax

        $sequence_9 = { 40 8bc8 c1e105 8bb9084c4200 0bb90c4c4200 75c8 5f }
            // n = 7, score = 100
            //   40                   | inc                 eax
            //   8bc8                 | mov                 ecx, eax
            //   c1e105               | shl                 ecx, 5
            //   8bb9084c4200         | mov                 edi, dword ptr [ecx + 0x424c08]
            //   0bb90c4c4200         | or                  edi, dword ptr [ecx + 0x424c0c]
            //   75c8                 | jne                 0xffffffca
            //   5f                   | pop                 edi

    condition:
        7 of them and filesize < 372736
}