rule win_ransomexx_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-11-21"
        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 = "20221118"
        malpedia_hash = "e0702e2e6d1d00da65c8a29a4ebacd0a4c59e1af"
        malpedia_version = "20221125"
        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 = { e8???????? 83c404 c705????????28b54100 e8???????? 6a00 }
            // n = 5, score = 100
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   c705????????28b54100     |     
            //   e8????????           |                     
            //   6a00                 | push                0

        $sequence_1 = { 57 6a6c 33ff 8d4594 57 50 }
            // n = 6, score = 100
            //   57                   | push                edi
            //   6a6c                 | push                0x6c
            //   33ff                 | xor                 edi, edi
            //   8d4594               | lea                 eax, [ebp - 0x6c]
            //   57                   | push                edi
            //   50                   | push                eax

        $sequence_2 = { c1ea0a 33fb 33fa 8b55d0 8bda c1c30e c1ca07 }
            // n = 7, score = 100
            //   c1ea0a               | shr                 edx, 0xa
            //   33fb                 | xor                 edi, ebx
            //   33fa                 | xor                 edi, edx
            //   8b55d0               | mov                 edx, dword ptr [ebp - 0x30]
            //   8bda                 | mov                 ebx, edx
            //   c1c30e               | rol                 ebx, 0xe
            //   c1ca07               | ror                 edx, 7

        $sequence_3 = { c1e717 894c2438 33c9 0bcb 33db b808000000 }
            // n = 6, score = 100
            //   c1e717               | shl                 edi, 0x17
            //   894c2438             | mov                 dword ptr [esp + 0x38], ecx
            //   33c9                 | xor                 ecx, ecx
            //   0bcb                 | or                  ecx, ebx
            //   33db                 | xor                 ebx, ebx
            //   b808000000           | mov                 eax, 8

        $sequence_4 = { 8d45f4 50 51 6a02 52 ffd6 85c0 }
            // n = 7, score = 100
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   6a02                 | push                2
            //   52                   | push                edx
            //   ffd6                 | call                esi
            //   85c0                 | test                eax, eax

        $sequence_5 = { 83f801 0f84b3000000 8b1d???????? 83f803 7559 b8cdcccccc f765e8 }
            // n = 7, score = 100
            //   83f801               | cmp                 eax, 1
            //   0f84b3000000         | je                  0xb9
            //   8b1d????????         |                     
            //   83f803               | cmp                 eax, 3
            //   7559                 | jne                 0x5b
            //   b8cdcccccc           | mov                 eax, 0xcccccccd
            //   f765e8               | mul                 dword ptr [ebp - 0x18]

        $sequence_6 = { bb01000000 8b45fc 85c0 7407 50 ff15???????? 8b45f8 }
            // n = 7, score = 100
            //   bb01000000           | mov                 ebx, 1
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   85c0                 | test                eax, eax
            //   7407                 | je                  9
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8b45f8               | mov                 eax, dword ptr [ebp - 8]

        $sequence_7 = { 7c98 51 e8???????? 83c404 c705????????28b54100 e8???????? }
            // n = 6, score = 100
            //   7c98                 | jl                  0xffffff9a
            //   51                   | push                ecx
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   c705????????28b54100     |     
            //   e8????????           |                     

        $sequence_8 = { 8b8b38010000 56 8d957cfeffff 52 50 ffd1 83c418 }
            // n = 7, score = 100
            //   8b8b38010000         | mov                 ecx, dword ptr [ebx + 0x138]
            //   56                   | push                esi
            //   8d957cfeffff         | lea                 edx, [ebp - 0x184]
            //   52                   | push                edx
            //   50                   | push                eax
            //   ffd1                 | call                ecx
            //   83c418               | add                 esp, 0x18

        $sequence_9 = { 6a04 8d45e8 6a00 50 ffd1 a1???????? 6a04 }
            // n = 7, score = 100
            //   6a04                 | push                4
            //   8d45e8               | lea                 eax, [ebp - 0x18]
            //   6a00                 | push                0
            //   50                   | push                eax
            //   ffd1                 | call                ecx
            //   a1????????           |                     
            //   6a04                 | push                4

    condition:
        7 of them and filesize < 372736
}