rule win_minifast_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.minifast."
        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.minifast"
        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 = { 8b08 81f187000000 81f187000000 48b8365e1d1f4d10db70 480305???????? 8908 48b8365e1d1f4d10db70 }
            // n = 7, score = 100
            //   8b08                 | xor                 edx, edx
            //   81f187000000         | div                 ecx
            //   81f187000000         | sub                 eax, 0x17
            //   48b8365e1d1f4d10db70     | add    eax, 0x17
            //   480305????????       |                     
            //   8908                 | imul                eax, eax, 0x14
            //   48b8365e1d1f4d10db70     | mov    ecx, 0x14

        $sequence_1 = { 89c8 4421c0 09c3 83f3ff 81f3447a9651 81e3447a9651 b8ffffffff }
            // n = 7, score = 100
            //   89c8                 | inc                 eax
            //   4421c0               | or                  dh, dl
            //   09c3                 | inc                 eax
            //   83f3ff               | mov                 dl, bh
            //   81f3447a9651         | xor                 dl, 0xff
            //   81e3447a9651         | inc                 ecx
            //   b8ffffffff           | mov                 cl, bl

        $sequence_2 = { 48b9e98f99ea57c6dc4e 4829c8 488985d0000000 4883bd1801000000 7505 e9???????? 48b8dc5b9dd112100499 }
            // n = 7, score = 100
            //   48b9e98f99ea57c6dc4e     | mov    eax, 0xe81e1864
            //   4829c8               | stosd               dword ptr es:[edi], eax
            //   488985d0000000       | in                  al, 6
            //   4883bd1801000000     | ror                 dword ptr [edx - 0x75], cl
            //   7505                 | add                 al, 0
            //   e9????????           |                     
            //   48b8dc5b9dd112100499     | dec    ecx

        $sequence_3 = { 80f2ff 80e2d0 4180e1ff 4508d0 4408ca 4130d0 4188f9 }
            // n = 7, score = 100
            //   80f2ff               | adc                 bl, byte ptr [edx + ebx*4 + 0x4de1ba48]
            //   80e2d0               | push                0xfa7c4ef9
            //   4180e1ff             | and                 cl, byte ptr [eax - 0x7f]
            //   4508d0               | ret                 0xb12
            //   4408ca               | add                 byte ptr [eax], al
            //   4130d0               | dec                 eax
            //   4188f9               | lea                 ecx, [0x144966]

        $sequence_4 = { e9???????? 8b05???????? 8944240c 8b0d???????? 89ca 83e2ff 4189d0 }
            // n = 7, score = 100
            //   e9????????           |                     
            //   8b05????????         |                     
            //   8944240c             | and                 bl, 0xc6
            //   8b0d????????         |                     
            //   89ca                 | inc                 ecx
            //   83e2ff               | mov                 bl, 0xff
            //   4189d0               | inc                 ecx

        $sequence_5 = { ffd0 4c8b442420 488b4c2428 4889c2 49b96a7540380775b1cc 4c030d???????? 48b8a5c1773d4be9680e }
            // n = 7, score = 100
            //   ffd0                 | mov                 dword ptr [esp + 8], eax
            //   4c8b442420           | je                  0xa42
            //   488b4c2428           | mov                 eax, dword ptr [esp + 8]
            //   4889c2               | jmp                 0x88b
            //   49b96a7540380775b1cc     | mov    ecx, dword ptr [esp + 0xc]
            //   4c030d????????       |                     
            //   48b8a5c1773d4be9680e     | xor    eax, eax

        $sequence_6 = { b2ff 80f222 4188f2 4180f2ff 41b0ff 4180f01a 4188d1 }
            // n = 7, score = 100
            //   b2ff                 | div                 ecx
            //   80f222               | mov                 ecx, eax
            //   4188f2               | mov                 eax, dword ptr [eax]
            //   4180f2ff             | add                 eax, 0x23
            //   41b0ff               | imul                eax, eax, 0x30
            //   4180f01a             | mov                 ecx, 0x30
            //   4188d1               | xor                 edx, edx

        $sequence_7 = { ffd0 4883c420 488b4550 48833800 0f95c0 88455f 48b8a6953f852b4c1be0 }
            // n = 7, score = 100
            //   ffd0                 | dec                 esp
            //   4883c420             | mov                 dword ptr [ebp], ebx
            //   488b4550             | dec                 eax
            //   48833800             | sub                 esp, eax
            //   0f95c0               | dec                 eax
            //   88455f               | sub                 esp, eax
            //   48b8a6953f852b4c1be0     | dec    eax

        $sequence_8 = { 80f2ff 80e2d7 41b2ff 4180f2d7 4520d3 41b0ff 4180f0ff }
            // n = 7, score = 100
            //   80f2ff               | push                0xfa7c4ef9
            //   80e2d7               | and                 cl, byte ptr [eax - 0x7f]
            //   41b2ff               | ret                 0xb12
            //   4180f2d7             | add                 byte ptr [eax], al
            //   4520d3               | dec                 eax
            //   41b0ff               | lea                 ecx, [0x1447b7]
            //   4180f0ff             | call                eax

        $sequence_9 = { 8b1401 88d1 440fb6d9 4489d9 4869c925499224 48c1e920 4189c9 }
            // n = 7, score = 100
            //   8b1401               | add                 byte ptr [eax - 0x48], cl
            //   88d1                 | loope               0x19f8
            //   440fb6d9             | push                0xfa7c4ef9
            //   4489d9               | and                 cl, byte ptr [ecx - 0x1e47b7f8]
            //   4869c925499224       | dec                 ebp
            //   48c1e920             | push                0xfa7c4ef9
            //   4189c9               | and                 cl, byte ptr [ebx - 0x300e7ef8]

    condition:
        7 of them and filesize < 5141504
}