rule win_ashen_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.ashen."
        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.ashen"
        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 = { 488bc3 498784fd504e0200 4885c0 7409 }
            // n = 4, score = 100
            //   488bc3               | lea                 edx, [0xf3ad]
            //   498784fd504e0200     | xor                 ecx, ecx
            //   4885c0               | dec                 eax
            //   7409                 | add                 edx, 2

        $sequence_1 = { e9???????? 81fa18070000 774c b92d000000 4c8d0d95df0000 33f6 448bd6 }
            // n = 7, score = 100
            //   e9????????           |                     
            //   81fa18070000         | lea                 edi, [0x180f4]
            //   774c                 | dec                 eax
            //   b92d000000           | mov                 eax, ecx
            //   4c8d0d95df0000       | and                 ecx, 0x3f
            //   33f6                 | dec                 eax
            //   448bd6               | sar                 eax, 6

        $sequence_2 = { 418bc2 41ffc2 8d0c92 03c9 2bc1 4898 0fb6843048f60100 }
            // n = 7, score = 100
            //   418bc2               | lea                 ecx, [0xe1ec]
            //   41ffc2               | dec                 eax
            //   8d0c92               | mov                 eax, dword ptr [ebx + 8]
            //   03c9                 | dec                 eax
            //   2bc1                 | lea                 ecx, [0x1d8dc]
            //   4898                 | dec                 eax
            //   0fb6843048f60100     | mov                 edi, eax

        $sequence_3 = { 488bc8 488bf8 e8???????? c6043b00 4885ff 7445 }
            // n = 6, score = 100
            //   488bc8               | lea                 ecx, [eax + 0x14]
            //   488bf8               | dec                 eax
            //   e8????????           |                     
            //   c6043b00             | test                eax, eax
            //   4885ff               | dec                 esp
            //   7445                 | lea                 eax, [0x2e]

        $sequence_4 = { d1f8 4863e8 4c8bf5 4d03f6 4b8b94f790b80100 e8???????? 85c0 }
            // n = 7, score = 100
            //   d1f8                 | inc                 ecx
            //   4863e8               | call                ecx
            //   4c8bf5               | test                eax, eax
            //   4d03f6               | jne                 0xdaa
            //   4b8b94f790b80100     | dec                 eax
            //   e8????????           |                     
            //   85c0                 | mov                 ecx, dword ptr [esp + 0x40]

        $sequence_5 = { 4883ec40 488b05???????? 4833c4 4889442430 488bb424a0000000 488d1d4b850100 }
            // n = 6, score = 100
            //   4883ec40             | inc                 ecx
            //   488b05????????       |                     
            //   4833c4               | inc                 edx
            //   4889442430           | cmp                 byte ptr [eax + 0x1fba0], 0x3f
            //   488bb424a0000000     | jbe                 0x6f9
            //   488d1d4b850100       | sub                 ecx, edi

        $sequence_6 = { 4883ec28 803d????????00 754c 488d0d28610100 }
            // n = 4, score = 100
            //   4883ec28             | inc                 edx
            //   803d????????00       |                     
            //   754c                 | mov                 byte ptr [edi + esi], 0
            //   488d0d28610100       | inc                 esp

        $sequence_7 = { 488d0d4eda0100 e8???????? 4c8bf8 498bd6 6666660f1f840000000000 }
            // n = 5, score = 100
            //   488d0d4eda0100       | inc                 ecx
            //   e8????????           |                     
            //   4c8bf8               | cmp                 eax, 4
            //   498bd6               | jle                 0xe8
            //   6666660f1f840000000000     | add    eax, edi

        $sequence_8 = { 8364246000 488d35eecd0100 bd00010000 4c8d4c2460 8bd5 448d47f6 488bce }
            // n = 7, score = 100
            //   8364246000           | je                  0xa87
            //   488d35eecd0100       | inc                 cx
            //   bd00010000           | cmp                 ebx, dword ptr [eax]
            //   4c8d4c2460           | jne                 0x98c
            //   8bd5                 | sub                 eax, dword ptr [esp + 0x48]
            //   448d47f6             | mov                 edx, 0x26
            //   488bce               | mov                 dword ptr [esp + 0x30], eax

        $sequence_9 = { 0f114170 0f118980000000 48898190000000 488d05fc140000 498b0b 4889458f 488b454f }
            // n = 7, score = 100
            //   0f114170             | dec                 ecx
            //   0f118980000000       | mov                 ecx, ebp
            //   48898190000000       | dec                 eax
            //   488d05fc140000       | test                eax, eax
            //   498b0b               | je                  0x32d
            //   4889458f             | dec                 eax
            //   488b454f             | mov                 ecx, 0xffffffff

    condition:
        7 of them and filesize < 348160
}