rule win_shrinklocker_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.shrinklocker."
        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.shrinklocker"
        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 = { 488d4c2448 e8???????? 90 e9???????? 488b4c2470 e8???????? 4c8bc0 }
            // n = 7, score = 100
            //   488d4c2448           | mov                 dword ptr [esp + 0x134], 0
            //   e8????????           |                     
            //   90                   | mov                 dword ptr [esp + 0x140], 0
            //   e9????????           |                     
            //   488b4c2470           | mov                 dword ptr [esp + 0x28], 0
            //   e8????????           |                     
            //   4c8bc0               | dec                 eax

        $sequence_1 = { 4889442440 488d4c2470 e8???????? 4889442438 488b542438 488b4c2440 e8???????? }
            // n = 7, score = 100
            //   4889442440           | jne                 0xac
            //   488d4c2470           | dec                 eax
            //   e8????????           |                     
            //   4889442438           | mov                 eax, dword ptr [esp + 0x80]
            //   488b542438           | jae                 0x4e9
            //   488b4c2440           | dec                 eax
            //   e8????????           |                     

        $sequence_2 = { 8b44245c 39442444 7608 8b44245c 89442444 837c244400 }
            // n = 6, score = 100
            //   8b44245c             | jmp                 0x617
            //   39442444             | dec                 eax
            //   7608                 | mov                 eax, dword ptr [esp + 8]
            //   8b44245c             | cmp                 dword ptr [eax + 0x1710], 8
            //   89442444             | jl                  0x617
            //   837c244400           | dec                 eax

        $sequence_3 = { 483bc8 480f42f0 488d4e01 4885c9 7504 33ff }
            // n = 6, score = 100
            //   483bc8               | dec                 eax
            //   480f42f0             | mov                 eax, dword ptr [esp + 8]
            //   488d4e01             | movzx               eax, word ptr [eax + 0x170c]
            //   4885c9               | and                 eax, 0xff
            //   7504                 | cmp                 dword ptr [eax + 0x1710], 0x10
            //   33ff                 | jne                 0x6c1

        $sequence_4 = { eb07 488d15f1500300 488d4c2420 e8???????? be01000000 83630800 488d05175e0200 }
            // n = 7, score = 100
            //   eb07                 | mov                 dword ptr [eax + 0x38], ecx
            //   488d15f1500300       | inc                 ecx
            //   488d4c2420           | mov                 eax, 0x1bf0
            //   e8????????           |                     
            //   be01000000           | mov                 edx, 1
            //   83630800             | dec                 eax
            //   488d05175e0200       | mov                 eax, dword ptr [esp + 0x40]

        $sequence_5 = { c1f803 89442420 488b842480000000 8b4c2420 8b4018 2bc1 }
            // n = 6, score = 100
            //   c1f803               | mov                 ecx, dword ptr [esp + 0x20]
            //   89442420             | lea                 eax, [ecx + eax - 0x10]
            //   488b842480000000     | dec                 eax
            //   8b4c2420             | mov                 ecx, dword ptr [esp + 0x60]
            //   8b4018               | mov                 word ptr [ecx + 0x170c], ax
            //   2bc1                 | dec                 eax

        $sequence_6 = { 8d4401f0 488b4c2460 898110170000 eb48 0fb744240c 488b4c2460 8b8910170000 }
            // n = 7, score = 100
            //   8d4401f0             | sub                 esp, 0x20
            //   488b4c2460           | dec                 eax
            //   898110170000         | mov                 eax, dword ptr [ecx + 0xf8]
            //   eb48                 | dec                 eax
            //   0fb744240c           | mov                 ebx, ecx
            //   488b4c2460           | dec                 eax
            //   8b8910170000         | test                eax, eax

        $sequence_7 = { 83f801 751b 488b4308 488b08 488d0534070200 483901 7408 }
            // n = 7, score = 100
            //   83f801               | lea                 ecx, [esp + 0x4e0]
            //   751b                 | inc                 ecx
            //   488b4308             | mov                 ecx, 0x100
            //   488b08               | inc                 ecx
            //   488d0534070200       | mov                 eax, 0x3e9
            //   483901               | dec                 eax
            //   7408                 | lea                 edx, [esp + 0x310]

        $sequence_8 = { 7578 48630df866feff 488d15b566feff 4803ca 813950450000 755f b80b020000 }
            // n = 7, score = 100
            //   7578                 | movzx               eax, word ptr [esp + 0x44]
            //   48630df866feff       | dec                 eax
            //   488d15b566feff       | mov                 ecx, dword ptr [esp + 0x70]
            //   4803ca               | mov                 edx, 0x10
            //   813950450000         | sub                 edx, dword ptr [ecx + 0x1710]
            //   755f                 | mov                 ecx, edx
            //   b80b020000           | sar                 eax, cl

        $sequence_9 = { 4889451f 33c0 488945c7 4183fe04 488d45b7 897dd7 4889442448 }
            // n = 7, score = 100
            //   4889451f             | dec                 eax
            //   33c0                 | mov                 eax, dword ptr [esp + 0x110]
            //   488945c7             | dec                 eax
            //   4183fe04             | mov                 ecx, dword ptr [esp + 0x68]
            //   488d45b7             | dec                 eax
            //   897dd7               | mov                 dword ptr [eax + 0x10], ecx
            //   4889442448           | dec                 eax

    condition:
        7 of them and filesize < 10490880
}