rule win_yakuza_ransomware_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.yakuza_ransomware."
        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.yakuza_ransomware"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 33f6 66837d08ff 8b480c 0fb7d6 7410 8b4904 52 }
            // n = 7, score = 100
            //   33f6                 | xor                 esi, esi
            //   66837d08ff           | cmp                 word ptr [ebp + 8], -1
            //   8b480c               | mov                 ecx, dword ptr [eax + 0xc]
            //   0fb7d6               | movzx               edx, si
            //   7410                 | je                  0x12
            //   8b4904               | mov                 ecx, dword ptr [ecx + 4]
            //   52                   | push                edx

        $sequence_1 = { e8???????? 8bf0 83c410 89b55cfdffff c645fc17 0f57c0 0f1106 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   83c410               | add                 esp, 0x10
            //   89b55cfdffff         | mov                 dword ptr [ebp - 0x2a4], esi
            //   c645fc17             | mov                 byte ptr [ebp - 4], 0x17
            //   0f57c0               | xorps               xmm0, xmm0
            //   0f1106               | movups              xmmword ptr [esi], xmm0

        $sequence_2 = { ffd2 ffb53cffffff 8b9548ffffff 8b8d40ffffff 52 ffb538ffffff ffb524ffffff }
            // n = 7, score = 100
            //   ffd2                 | call                edx
            //   ffb53cffffff         | push                dword ptr [ebp - 0xc4]
            //   8b9548ffffff         | mov                 edx, dword ptr [ebp - 0xb8]
            //   8b8d40ffffff         | mov                 ecx, dword ptr [ebp - 0xc0]
            //   52                   | push                edx
            //   ffb538ffffff         | push                dword ptr [ebp - 0xc8]
            //   ffb524ffffff         | push                dword ptr [ebp - 0xdc]

        $sequence_3 = { 8b4df0 83e950 e9???????? 8b4df0 e9???????? 8b542408 8d420c }
            // n = 7, score = 100
            //   8b4df0               | mov                 ecx, dword ptr [ebp - 0x10]
            //   83e950               | sub                 ecx, 0x50
            //   e9????????           |                     
            //   8b4df0               | mov                 ecx, dword ptr [ebp - 0x10]
            //   e9????????           |                     
            //   8b542408             | mov                 edx, dword ptr [esp + 8]
            //   8d420c               | lea                 eax, [edx + 0xc]

        $sequence_4 = { eb03 0fb3c8 8902 83f91f 7303 41 ebda }
            // n = 7, score = 100
            //   eb03                 | jmp                 5
            //   0fb3c8               | btr                 eax, ecx
            //   8902                 | mov                 dword ptr [edx], eax
            //   83f91f               | cmp                 ecx, 0x1f
            //   7303                 | jae                 5
            //   41                   | inc                 ecx
            //   ebda                 | jmp                 0xffffffdc

        $sequence_5 = { 23c3 f7d1 3344247c 23cd 334c2478 89842444010000 8bc5 }
            // n = 7, score = 100
            //   23c3                 | and                 eax, ebx
            //   f7d1                 | not                 ecx
            //   3344247c             | xor                 eax, dword ptr [esp + 0x7c]
            //   23cd                 | and                 ecx, ebp
            //   334c2478             | xor                 ecx, dword ptr [esp + 0x78]
            //   89842444010000       | mov                 dword ptr [esp + 0x144], eax
            //   8bc5                 | mov                 eax, ebp

        $sequence_6 = { 8b12 8b4d08 83791408 8b7910 7202 8b09 3bf7 }
            // n = 7, score = 100
            //   8b12                 | mov                 edx, dword ptr [edx]
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   83791408             | cmp                 dword ptr [ecx + 0x14], 8
            //   8b7910               | mov                 edi, dword ptr [ecx + 0x10]
            //   7202                 | jb                  4
            //   8b09                 | mov                 ecx, dword ptr [ecx]
            //   3bf7                 | cmp                 esi, edi

        $sequence_7 = { e8???????? 83c404 f6c310 742d 83e3ef 895d60 8b4dd0 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   f6c310               | test                bl, 0x10
            //   742d                 | je                  0x2f
            //   83e3ef               | and                 ebx, 0xffffffef
            //   895d60               | mov                 dword ptr [ebp + 0x60], ebx
            //   8b4dd0               | mov                 ecx, dword ptr [ebp - 0x30]

        $sequence_8 = { 83c40c 8b45d8 c1f802 8d0486 894704 c785c0fbffff00000000 c645fc05 }
            // n = 7, score = 100
            //   83c40c               | add                 esp, 0xc
            //   8b45d8               | mov                 eax, dword ptr [ebp - 0x28]
            //   c1f802               | sar                 eax, 2
            //   8d0486               | lea                 eax, [esi + eax*4]
            //   894704               | mov                 dword ptr [edi + 4], eax
            //   c785c0fbffff00000000     | mov    dword ptr [ebp - 0x440], 0
            //   c645fc05             | mov                 byte ptr [ebp - 4], 5

        $sequence_9 = { e9???????? 83e908 e9???????? 2b49fc 81e910010000 e9???????? 83e904 }
            // n = 7, score = 100
            //   e9????????           |                     
            //   83e908               | sub                 ecx, 8
            //   e9????????           |                     
            //   2b49fc               | sub                 ecx, dword ptr [ecx - 4]
            //   81e910010000         | sub                 ecx, 0x110
            //   e9????????           |                     
            //   83e904               | sub                 ecx, 4

    condition:
        7 of them and filesize < 2811904
}