rule win_chairsmack_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.chairsmack."
        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.chairsmack"
        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 = { 56 8b7508 57 8b7d0c 894df0 3bf7 7451 }
            // n = 7, score = 200
            //   56                   | push                esi
            //   8b7508               | mov                 esi, dword ptr [ebp + 8]
            //   57                   | push                edi
            //   8b7d0c               | mov                 edi, dword ptr [ebp + 0xc]
            //   894df0               | mov                 dword ptr [ebp - 0x10], ecx
            //   3bf7                 | cmp                 esi, edi
            //   7451                 | je                  0x53

        $sequence_1 = { e8???????? 8d8424a8010000 50 8d8c24c4020000 e8???????? 68???????? 8d4c244c }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8d8424a8010000       | lea                 eax, [esp + 0x1a8]
            //   50                   | push                eax
            //   8d8c24c4020000       | lea                 ecx, [esp + 0x2c4]
            //   e8????????           |                     
            //   68????????           |                     
            //   8d4c244c             | lea                 ecx, [esp + 0x4c]

        $sequence_2 = { c7466080834800 c745fc00000000 8b06 c745f001000000 }
            // n = 4, score = 200
            //   c7466080834800       | mov                 dword ptr [esi + 0x60], 0x488380
            //   c745fc00000000       | mov                 dword ptr [ebp - 4], 0
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   c745f001000000       | mov                 dword ptr [ebp - 0x10], 1

        $sequence_3 = { 8d8c24a0000000 e8???????? 68???????? 8d8c24a0000000 c684248403000067 e8???????? }
            // n = 6, score = 200
            //   8d8c24a0000000       | lea                 ecx, [esp + 0xa0]
            //   e8????????           |                     
            //   68????????           |                     
            //   8d8c24a0000000       | lea                 ecx, [esp + 0xa0]
            //   c684248403000067     | mov                 byte ptr [esp + 0x384], 0x67
            //   e8????????           |                     

        $sequence_4 = { e8???????? 6aff 6a00 8d842488000000 50 8d4c2454 e8???????? }
            // n = 7, score = 200
            //   e8????????           |                     
            //   6aff                 | push                -1
            //   6a00                 | push                0
            //   8d842488000000       | lea                 eax, [esp + 0x88]
            //   50                   | push                eax
            //   8d4c2454             | lea                 ecx, [esp + 0x54]
            //   e8????????           |                     

        $sequence_5 = { c684242801000015 e8???????? 68???????? 8d8c24dc000000 e8???????? 6aff }
            // n = 6, score = 200
            //   c684242801000015     | mov                 byte ptr [esp + 0x128], 0x15
            //   e8????????           |                     
            //   68????????           |                     
            //   8d8c24dc000000       | lea                 ecx, [esp + 0xdc]
            //   e8????????           |                     
            //   6aff                 | push                -1

        $sequence_6 = { 6a00 6a50 56 50 ff15???????? 8bf0 85f6 }
            // n = 7, score = 200
            //   6a00                 | push                0
            //   6a50                 | push                0x50
            //   56                   | push                esi
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8bf0                 | mov                 esi, eax
            //   85f6                 | test                esi, esi

        $sequence_7 = { c1fa05 8b85f0efffff 83e01f c1e006 8b0c95d06d4a00 837c013000 }
            // n = 6, score = 200
            //   c1fa05               | sar                 edx, 5
            //   8b85f0efffff         | mov                 eax, dword ptr [ebp - 0x1010]
            //   83e01f               | and                 eax, 0x1f
            //   c1e006               | shl                 eax, 6
            //   8b0c95d06d4a00       | mov                 ecx, dword ptr [edx*4 + 0x4a6dd0]
            //   837c013000           | cmp                 dword ptr [ecx + eax + 0x30], 0

        $sequence_8 = { 894618 33c0 c7471807000000 c7471400000000 66894704 8bc6 5f }
            // n = 7, score = 200
            //   894618               | mov                 dword ptr [esi + 0x18], eax
            //   33c0                 | xor                 eax, eax
            //   c7471807000000       | mov                 dword ptr [edi + 0x18], 7
            //   c7471400000000       | mov                 dword ptr [edi + 0x14], 0
            //   66894704             | mov                 word ptr [edi + 4], ax
            //   8bc6                 | mov                 eax, esi
            //   5f                   | pop                 edi

        $sequence_9 = { 51 8b4dfc e8???????? 8b45fc 8be5 5d c21000 }
            // n = 7, score = 200
            //   51                   | push                ecx
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   e8????????           |                     
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   8be5                 | mov                 esp, ebp
            //   5d                   | pop                 ebp
            //   c21000               | ret                 0x10

    condition:
        7 of them and filesize < 1974272
}