rule win_ryuk_stealer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        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 = "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 = { 50 e8???????? 83c40c ff15???????? 33d2 b910270000 }
            // n = 6, score = 800
            //   50                   | push                eax
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   ff15????????         |                     
            //   33d2                 | xor                 edx, edx
            //   b910270000           | mov                 ecx, 0x2710

        $sequence_1 = { 99 b9a0860100 f7f9 81c2a8610000 52 }
            // n = 5, score = 800
            //   99                   | cdq                 
            //   b9a0860100           | mov                 ecx, 0x186a0
            //   f7f9                 | idiv                ecx
            //   81c2a8610000         | add                 edx, 0x61a8
            //   52                   | push                edx

        $sequence_2 = { 50 0fb7447302 50 e8???????? }
            // n = 4, score = 800
            //   50                   | push                eax
            //   0fb7447302           | movzx               eax, word ptr [ebx + esi*2 + 2]
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_3 = { ff15???????? 8d442454 50 ff15???????? 50 ff15???????? }
            // n = 6, score = 800
            //   ff15????????         |                     
            //   8d442454             | lea                 eax, [esp + 0x54]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_4 = { 83f805 740a b9???????? e8???????? 46 83fe1a }
            // n = 6, score = 800
            //   83f805               | cmp                 eax, 5
            //   740a                 | je                  0xc
            //   b9????????           |                     
            //   e8????????           |                     
            //   46                   | inc                 esi
            //   83fe1a               | cmp                 esi, 0x1a

        $sequence_5 = { 83f805 740a b9???????? e8???????? 46 }
            // n = 5, score = 800
            //   83f805               | cmp                 eax, 5
            //   740a                 | je                  0xc
            //   b9????????           |                     
            //   e8????????           |                     
            //   46                   | inc                 esi

        $sequence_6 = { 68???????? 66a3???????? ff15???????? 83f805 740a b9???????? e8???????? }
            // n = 7, score = 800
            //   68????????           |                     
            //   66a3????????         |                     
            //   ff15????????         |                     
            //   83f805               | cmp                 eax, 5
            //   740a                 | je                  0xc
            //   b9????????           |                     
            //   e8????????           |                     

        $sequence_7 = { 8be5 5d c3 ff35???????? 8b35???????? ffd6 }
            // n = 6, score = 800
            //   8be5                 | mov                 esp, ebp
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   ff35????????         |                     
            //   8b35????????         |                     
            //   ffd6                 | call                esi

        $sequence_8 = { ff15???????? 8d442454 50 ff15???????? 50 }
            // n = 5, score = 800
            //   ff15????????         |                     
            //   8d442454             | lea                 eax, [esp + 0x54]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   50                   | push                eax

        $sequence_9 = { f7f9 81c2a8610000 52 ff15???????? }
            // n = 4, score = 800
            //   f7f9                 | idiv                ecx
            //   81c2a8610000         | add                 edx, 0x61a8
            //   52                   | push                edx
            //   ff15????????         |                     

    condition:
        7 of them and filesize < 368640
}