rule win_ransomexx_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        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 = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 8b443454 8d4c2414 8d9424a8000000 51 89542430 897c2428 8944242c }
            // n = 7, score = 100
            //   8b443454             | mov                 eax, dword ptr [esp + esi + 0x54]
            //   8d4c2414             | lea                 ecx, [esp + 0x14]
            //   8d9424a8000000       | lea                 edx, [esp + 0xa8]
            //   51                   | push                ecx
            //   89542430             | mov                 dword ptr [esp + 0x30], edx
            //   897c2428             | mov                 dword ptr [esp + 0x28], edi
            //   8944242c             | mov                 dword ptr [esp + 0x2c], eax

        $sequence_1 = { 0f8532040000 03db 8d75d0 e8???????? 8bf0 85f6 0f851e040000 }
            // n = 7, score = 100
            //   0f8532040000         | jne                 0x438
            //   03db                 | add                 ebx, ebx
            //   8d75d0               | lea                 esi, [ebp - 0x30]
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   85f6                 | test                esi, esi
            //   0f851e040000         | jne                 0x424

        $sequence_2 = { 51 6a02 52 ffd6 85c0 7405 bb01000000 }
            // n = 7, score = 100
            //   51                   | push                ecx
            //   6a02                 | push                2
            //   52                   | push                edx
            //   ffd6                 | call                esi
            //   85c0                 | test                eax, eax
            //   7405                 | je                  7
            //   bb01000000           | mov                 ebx, 1

        $sequence_3 = { 0fb6b688614200 c1e108 33ce 338a886a4200 8b7004 3308 8b7808 }
            // n = 7, score = 100
            //   0fb6b688614200       | movzx               esi, byte ptr [esi + 0x426188]
            //   c1e108               | shl                 ecx, 8
            //   33ce                 | xor                 ecx, esi
            //   338a886a4200         | xor                 ecx, dword ptr [edx + 0x426a88]
            //   8b7004               | mov                 esi, dword ptr [eax + 4]
            //   3308                 | xor                 ecx, dword ptr [eax]
            //   8b7808               | mov                 edi, dword ptr [eax + 8]

        $sequence_4 = { 8bfc 85ff 0f8486000000 8bcf 8bf7 8bd7 33c0 }
            // n = 7, score = 100
            //   8bfc                 | mov                 edi, esp
            //   85ff                 | test                edi, edi
            //   0f8486000000         | je                  0x8c
            //   8bcf                 | mov                 ecx, edi
            //   8bf7                 | mov                 esi, edi
            //   8bd7                 | mov                 edx, edi
            //   33c0                 | xor                 eax, eax

        $sequence_5 = { 50 51 ff15???????? 85c0 7439 8d8dfcfeffff 51 }
            // n = 7, score = 100
            //   50                   | push                eax
            //   51                   | push                ecx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7439                 | je                  0x3b
            //   8d8dfcfeffff         | lea                 ecx, [ebp - 0x104]
            //   51                   | push                ecx

        $sequence_6 = { 7425 3bc8 7321 8b5496fc 33db }
            // n = 5, score = 100
            //   7425                 | je                  0x27
            //   3bc8                 | cmp                 ecx, eax
            //   7321                 | jae                 0x23
            //   8b5496fc             | mov                 edx, dword ptr [esi + edx*4 - 4]
            //   33db                 | xor                 ebx, ebx

        $sequence_7 = { ff15???????? 50 ff15???????? 6a00 57 ff15???????? 57 }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   50                   | push                eax
            //   ff15????????         |                     
            //   6a00                 | push                0
            //   57                   | push                edi
            //   ff15????????         |                     
            //   57                   | push                edi

        $sequence_8 = { 8bfa 337c2448 8bde 335c244c 237c2450 235c2454 33fa }
            // n = 7, score = 100
            //   8bfa                 | mov                 edi, edx
            //   337c2448             | xor                 edi, dword ptr [esp + 0x48]
            //   8bde                 | mov                 ebx, esi
            //   335c244c             | xor                 ebx, dword ptr [esp + 0x4c]
            //   237c2450             | and                 edi, dword ptr [esp + 0x50]
            //   235c2454             | and                 ebx, dword ptr [esp + 0x54]
            //   33fa                 | xor                 edi, edx

        $sequence_9 = { 83c006 32903fb44100 885406ff 83f824 0f8c59ffffff a1???????? 8b4dec }
            // n = 7, score = 100
            //   83c006               | add                 eax, 6
            //   32903fb44100         | xor                 dl, byte ptr [eax + 0x41b43f]
            //   885406ff             | mov                 byte ptr [esi + eax - 1], dl
            //   83f824               | cmp                 eax, 0x24
            //   0f8c59ffffff         | jl                  0xffffff5f
            //   a1????????           |                     
            //   8b4dec               | mov                 ecx, dword ptr [ebp - 0x14]

    condition:
        7 of them and filesize < 372736
}