rule win_ryuk_stealer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.ryuk_stealer."
        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.ryuk_stealer"
        malpedia_rule_date = "20260422"
        malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
        malpedia_version = "20260504"
        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 = { 89442464 83c40c 66a1???????? 8bf2 }
            // n = 4, score = 800
            //   89442464             | mov                 dword ptr [esp + 0x64], eax
            //   83c40c               | add                 esp, 0xc
            //   66a1????????         |                     
            //   8bf2                 | mov                 esi, edx

        $sequence_1 = { 66a3???????? ff15???????? 83f805 740a b9???????? e8???????? 46 }
            // n = 7, score = 800
            //   66a3????????         |                     
            //   ff15????????         |                     
            //   83f805               | cmp                 eax, 5
            //   740a                 | je                  0xc
            //   b9????????           |                     
            //   e8????????           |                     
            //   46                   | inc                 esi

        $sequence_2 = { 0f8503070000 8d85b4fdffff 68???????? 50 e8???????? }
            // n = 5, score = 800
            //   0f8503070000         | jne                 0x709
            //   8d85b4fdffff         | lea                 eax, [ebp - 0x24c]
            //   68????????           |                     
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_3 = { 7414 6888130000 ff15???????? ff7604 ff15???????? 6810270000 }
            // n = 6, score = 800
            //   7414                 | je                  0x16
            //   6888130000           | push                0x1388
            //   ff15????????         |                     
            //   ff7604               | push                dword ptr [esi + 4]
            //   ff15????????         |                     
            //   6810270000           | push                0x2710

        $sequence_4 = { b9a0860100 f7f9 81c2a8610000 52 ff15???????? 46 }
            // n = 6, score = 800
            //   b9a0860100           | mov                 ecx, 0x186a0
            //   f7f9                 | idiv                ecx
            //   81c2a8610000         | add                 edx, 0x61a8
            //   52                   | push                edx
            //   ff15????????         |                     
            //   46                   | inc                 esi

        $sequence_5 = { 8bcb 0f44f2 42 8d7902 }
            // n = 4, score = 800
            //   8bcb                 | mov                 ecx, ebx
            //   0f44f2               | cmove               esi, edx
            //   42                   | inc                 edx
            //   8d7902               | lea                 edi, [ecx + 2]

        $sequence_6 = { e8???????? 99 b9a0860100 f7f9 81c2f8240100 52 ff15???????? }
            // n = 7, score = 800
            //   e8????????           |                     
            //   99                   | cdq                 
            //   b9a0860100           | mov                 ecx, 0x186a0
            //   f7f9                 | idiv                ecx
            //   81c2f8240100         | add                 edx, 0x124f8
            //   52                   | push                edx
            //   ff15????????         |                     

        $sequence_7 = { 6685c0 75f5 6a04 6800100000 }
            // n = 4, score = 800
            //   6685c0               | test                ax, ax
            //   75f5                 | jne                 0xfffffff7
            //   6a04                 | push                4
            //   6800100000           | push                0x1000

        $sequence_8 = { 8a443701 3c2f 7408 3c2d }
            // n = 4, score = 800
            //   8a443701             | mov                 al, byte ptr [edi + esi + 1]
            //   3c2f                 | cmp                 al, 0x2f
            //   7408                 | je                  0xa
            //   3c2d                 | cmp                 al, 0x2d

        $sequence_9 = { 75f4 a1???????? 8907 eb38 }
            // n = 4, score = 800
            //   75f4                 | jne                 0xfffffff6
            //   a1????????           |                     
            //   8907                 | mov                 dword ptr [edi], eax
            //   eb38                 | jmp                 0x3a

    condition:
        7 of them and filesize < 368640
}